After cutting back on sugar and carbs for a while, you understandably start to miss sweets. A common misconception is that you have to skip sweets to meet your goals, which isn’t the case at all. There are plenty of sugar alternatives that fit within the Primal and keto lifestyles, and stevia is one of them.
Stevia is widely used in the low carb community to satisfy sugar cravings or simply add a touch of sweetness to a hot beverage or dessert, but should it be? What is stevia? Is it safe? What is its effect on insulin, if any, and does it have a place in a Primal Blueprint eating strategy? Let’s investigate.
What Is Stevia?
A lot of people categorize stevia as an artificial sweetener, but it’s important to note that stevia is not an artificial sweetener at all – it’s a plant-derived natural alternative to sugar.
Stevia is an herbaceous family of plants, 240 species strong, that grows in sub-tropical and tropical America (mostly South and Central, but some North). Stevia the sweetener refers to stevia rebaudiana, the plant and its leaves, which you can grow and use as or with tea (it was traditionally paired with yerba mate in South America) or, dried and powdered, as a sugar substitute that you sprinkle on. It’s apparently quite easy to grow, according to the stevia seller who tries to get me to buy a plant or two whenever I’m at the Santa Monica farmers’ market, and the raw leaf is very sweet.
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The Sweet Compounds in Stevia: Stevioside and Rebaudioside
Most stevia you’ll come across isn’t in its raw, unprocessed form, but in powdered or liquid extract form. The “sweet” lies in the steviol glycosides – stevioside and rebaudioside – which are the natural compounds isolated in these extracts. Some products use just one, while others use both stevioside and rebaudioside. Stevioside is the most prevalent glycoside in stevia, and some say it provides the bitter aftertaste that people sometimes complain about; rebaudioside is said to be the better tasting steviol glycoside, with far less bitterness.
Most of the “raw or natural” stevia products use the full range of glycosides, but the more processed brands will most likely isolate one or more of the steviol glycosides. The popular Truvia brand of stevia products uses only rebaudioside, as do both PureVia and Enliten. Different brands provide different conversion rates, but compared to sucrose, stevioside is generally about 250-300 times as sweet and rebaudioside is about 350-450 times as sweet.
Is Stevia Safe, or Bad for You?
The government has approved only isolated steviol glycosides as safe to use in food. Whole or crude stevia is not Generally Recognized as Safe (GRAS) according to government standards.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5591507/table/Tab1/‘>2 This is due to lack of safety information, not so much the presence of known harmful effects.
Does Stevia Affect Insulin?
I wrote an extensive piece on whether artificial sweeteners spike blood sugar a while back. There is one in vitro study that showed stevioside acts directly on pancreatic beta cells to stimulate insulin secretion and another which shows similarly insulinotropic (insulin-producing) effects of rebaudioside, which may give you pause.
Insulin secretion sounds like an insulin spike, no? And since we tend to be wary of unneeded insulin spikes, maybe we should avoid stevia. It’s not so simple, of course. For one, this was an in vitro study, performed in a super-controlled laboratory petri dish type setting; this was not an in vivo study of animals or people eating stevia in a natural, organic way. The results of in vitro studies do not always match results when you try to replicate them in vivo (in a person).
Secondly, insulin secretion isn’t necessarily a bad thing. I mean, we need it to shuttle nutrients into cells, and we’d die without it. As I mentioned in the dairy post a while back, insulin is millions upon millions of years old. It’s been preserved throughout history because it’s an essential hormone. It’s not always the bad guy, especially if your insulin sensitivity is where it should be.
In fact, the evidence is mounting that stevia actually is an insulin sensitizer that can aid in glucose tolerance and clearance after a meal. The Japanese have been using stevia for decades in the treatment of type 2 diabetics. Let’s look at a few recent studies. In fructose-fed rats, a single instance of oral stevioside increased insulin sensitivity and reduced postprandial blood glucose in a dose-dependent manner. The same study also found that diabetic rats given stevioside required less exogenous insulin for the same effect. Taken together, these results suggest that stevia may not just be a good sugar substitute for diabetics, but an effective supplement for treatment of their insulin resistance.http://www.ncbi.nlm.nih.gov/pubmed/20303371‘>4 Another strike in stevia’s favor.
Stevia Side Effects
Allergy to stevia has been reported, but it is rare.
Most people do not experience side effects when using stevia, but some people do experience effects like:
- Gastrointestinal discomfort
Most often these effects are from using stevia that is mixed with sugar alcohols, like erythritol or xylitol. If you can tolerate sugar alcohols, you will probably be okay using combination stevia and sugar alcohol products. To be sure, start slow, and watch for symptoms.
Stevia is considered safe for the diabetic population, but sometimes it is combined with ingredients that affect carb count, like dextrose and maltodextrin. If you’re diabetic, check your ingredients label and carb counts before adding it to food.
Historically, stevia has been used as a form of birth control, so use of stevia may contribute to fertility issues.http://www.ncbi.nlm.nih.gov/pubmed/21089163‘>6 Alone, low-dose stevia lowered cholesterol without the potentially beneficial effect on HDL. It’s also useful to note that high-dose stevia negatively affected some toxic parameters – so don’t eat spoonfuls of stevia (not that you would) – but long term low-dose stevia was deemed safe.
I’ve said before that I think carb timing is relatively low on the hierarchy of things to care about. It’s not as important as what you’re eating or how much. I think it’s also less important than your macros—getting sufficient protein and experimenting with different levels of carb intake.
That said, if you want to experiment with carb timing, go for it. You won’t get a lot of guidance about how to do it, though, at least not from empirical research. I can’t find any studies that systematically vary carb intake, morning versus evening, among people eating anything like a Primal or paleo diet.
The good news, though, is that there isn’t an obviously wrong way to do this. Carb timing is unlikely to be the factor that makes or breaks your health, fitness, or longevity goals. Still, it might move the needle, so let’s get into it.
Rationales for Eating Carbs in the Morning
Insulin Sensitivity is Higher in the Morning
In my estimation, the best argument in favor of eating most of your carbs in the morning is that that’s when you’re most insulin sensitive. It makes sense to eat your carbs at the time your body is best equipped to handle them.
Eating a greater proportion of your carbs in the morning also seems to promote insulin sensitivity.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5341154/‘>3
For what it’s worth, this is also why proponents of chrononutrition advocate for eating more of your total calories in the morning. Doing so, they argue, takes advantage of the natural peak in insulin sensitivity and acts as a zeitgeber to entrain your circadian rhythm.
And yes, I usually skip breakfast myself. I also eat a fairly low-carb, and therefore low-insulin-producing, diet. I’m metabolically healthy. My sleep is top notch. I’m not worried about my glucose tolerance nor my circadian rhythm. Both are in tiptop shape. For me, skipping breakfast feels natural, and I like extending my overnight fast. Since it seems to have no ill effects, I’m sticking with that schedule for now, but I’m open to change.
To “Sleep Low” for Fitness Gains
This one is really about avoiding carbs in the evening more than eating them in the morning per se. Here’s how it works: In the afternoon or evening, do a high-intensity workout to deplete glycogen stores. Do not eat carbohydrates after. In the morning, do a low-intensity session, such as a light jog, then eat breakfast with a balance of carbs, fat, and protein.
The purpose of sleeping low is to force your body to upregulate fat metabolism. Researchers have studied this protocol among elite male triathletes. They compared men who ate carbohydrates spread across three meals to men who ate all their carbs at breakfast and lunch and then “slept low.” Both groups ate the same total amount of carbs and did the same workouts.
In one report, after three weeks of this training, the group that slept low scored significantly better on a test of muscular efficiency. They also performed better on a surpamaximal test—basically pedal until you (almost) puke—and a 10k run in simulated race conditions.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5188410/‘>5
Reasons to Eat Most of Your Carbs in the Evening
Carbs Affect Sleep
Carbohydrates increase tryptophan production. Tryptophan is a precursor of serotonin, which in turn converts to melatonin. Still with me?
Thus, the theory goes, eating carbs at night will boost melatonin production and, hence, promote sleep. It makes sense, and you can certainly try it, but there’s no concrete evidence it actually works. According to the one tiny study that has examined this effect, your best bet is to eat some high-glycemic carbs four hours before bedtime.https://pubmed.ncbi.nlm.nih.gov/20849868/‘>7 and college students who were or were not stressed before eatinghttps://academic.oup.com/jcem/article/87/8/3984/2847416‘>9
What does this mean? It is true that if you’re hoping to extend an overnight fast and promote fat burning, then eating a high-carb breakfast that raises insulin will be counter to that goal. If you’re specifically worried that it will tank your cortisol, though, it may not be the case.
However, there is also tremendous variability in individuals’ cortisol responses. Certain people may indeed do better avoiding carbs in the morning. Some practitioners advise individuals with adrenal issues and cortisol dysregulation to eat most of their carbs in the evening instead of the morning.
For Weight Loss?
A lot of people tout this benefit, but there is no real evidence to back it up. There are a couple poorly done studies, and one that showed that participants who ate carbs at dinner instead of lunch lost more weight than those who did the opposite. However, that was because they lost lean tissue in addition to fat.https://pubmed.ncbi.nlm.nih.gov/9435517/‘>11
After exercise, when glycogen stores have been depleted, muscle cells become more insulin sensitive.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019055/‘>13 This only applies if you’ve actually depleted your muscle glycogen, though. A nice long walk, 30-minute bike ride at an aerobic heart rate, or microworkout won’t do it.
What If You’re Trying to Build Muscle?
As a pre-workout, consuming a small amount of carbohydrate, 25 to 30 grams, may be beneficial. You don’t need to worry about having full glycogen tanks, though.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2928613/‘>15
Should You Eat Carbs Separately from Fat?
This is another one of those beliefs that makes sense on paper but doesn’t quite bear out in practice. The idea here is that when you eat carbs and fat together, the carbs raise insulin, which unlocks fat cells, which allows the fat you just ate to be easily shoved inside. In other words, carbs + fat = weight gain.
It can work like that, but it doesn’t have to. This is a much bigger concern if you are eating an excess of calories. If you’re consuming more energy than your body actually needs, and you’re potentiating the fat storage process, then yeah, you’ll end up storing body fat.
If you’re not consuming more energy than you need, you don’t need to worry. For example, in one study, two groups of patients ate a hypocaloric diet where carbs and fat were eaten either separately or together for six weeks. Both groups lost similar amounts of body fat and showed comparable reductions in plasma glucose and triglycerides. http://www.ajcn.org/cgi/content/abstract/26/11/1180‘>1 has shown that the function of immunity-related phagocytes, the cells that surround and engulf pathogens, is impaired for at least five hours after intake of simple sugars. Free radicals, or damaging oxygen atoms, have their heyday as well within the first few hours after sugar increases oxidative stresshttp://www.ncbi.nlm.nih.gov/pubmed/18469239?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=2&log$=relatedarticles&logdbfrom=pubmed‘>3 for more than 24 hours.
How to Recover From a Carb Binge
As bad as this sounds, it could be worse. If you follow a Primal or keto lifestyle and the carb overload was just a detour, you’ll come out of this generally as healthy as you were before the flub. You’ll experience the effects, and you may feel them more acutely than you did before you chose the low-carb path. This isn’t a bad thing. Nonetheless, after the dust settles, the worst thing you can end up with is maybe a cold you wouldn’t have gotten otherwise. Your system will realign itself pretty readily. After spending a couple days back on your regularly scheduled program, you’ll be as good as new.
How to Get Back Into Ketosis After Cheating on Keto
So, you want to get back into fighting shape as soon as possible. Here’s what to do:
- Scale back your carbs to where you were before you found yourself off-track.
- Make sure you are getting the correct balance of electrolytes. Read this article to understand why electrolytes are important while transitioning to ketosis and how to make sure you are getting adequate electrolytes.
- Consume sufficient high-quality fats, especially at first.
- Don’t overdo the cardio. You can ease back into more intense aerobic exercise once you’re fully transitioned.
- Consider intermittent fasting. You may have an easier time getting into ketosis for the long haul if you time-restrict food intake, which gets your body used to producing ketones.
How Long Does it Take to Get Back Into Ketosis?
You may wonder how long it will take to get back into ketosis after falling off. The answer is, it varies. It depends on how metabolically flexible you were before you started, how insulin-sensitive you are currently, how many carbs you were accustomed to consuming before you increased your carb intake… there are a lot of factors. The vague answer is, it won’t take long to get back. Start now, and you’ll get to where you want to be before you know it.
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One of the more common questions we get in the Keto Reset Facebook community is, “How do I break through a weight-loss plateau?”
Stalls are frustrating. You’re cruising along on your Primal or Primal + keto diet, and then wham—you hit a wall. It’s all a totally normal and expected part of the weight loss process. Weight loss is never linear. There are always downs, ups, and flat spots.
In fact, if you’ve been losing weight for a while, and then you stall out for a week or two, I wouldn’t even consider that a plateau necessarily. Your body might keep losing weight on its own if you give it time and don’t stress about it. Still, I get it, you’re eager to kick-start the weight loss again.
One strategy that gets tossed around is trying a carb refeed or “carb up.” Carb refeeds are touted as plateau busters and also, more generally, as a strategy to support weight loss. In today’s post, I’ll explain the logic behind this idea and explain why it might be effective, especially for women following a generally low-carb approach.
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What Is a Carb Refeed?
Let’s get some terminology out of the way. Strategically adding carbs to a low-carb diet is variously called a “carb refeed,” “carb up,” or “carb cycle.” These terms don’t have standardized definitions. In general, carb cycling usually refers to eating low carb for a certain number of days, then higher carb for a certain number of days, and repeating.
“Carb refeed” and “carb up” can mean the same thing, or they can mean adding carbs more intuitively when you feel like you need them.
Carb cycling strategies have long been used to promote leanness, especially by physique and other athletes trying to achieve low body fat percentages. In this context, carb cycling involves specific protocols, usually 5-6 days of very low carb eating combined with 1-2 days of higher carb eating. They may include exercise and fasting regimens, too.
The carb cycling protocols used for getting super lean aren’t the same as what we’ll be talking about for general weight loss and breaking out of a stall. For one thing, they usually involve more carbs than you probably need. We’ll get to that later. Also, although some of the mechanisms are probably the same, they focus specifically on depleting and refilling glycogen stores. For our purposes, that’s not so important.
How Do Carb Refeeds Work?
First let me say that the evidence for carb cycling strategies, especially with regard to weight loss and plateaus, is mostly anecdotal. There is pretty good data to support the pieces, but the whole picture has not been rigorously tested.
So what do we think is happening? There are a few (not mutually exclusive) hypotheses here:
- Carb refeeds work by boosting leptin
- Carb refeeds work by relieving the stress of dieting
- Dieting is hard, and carb refeeds help us stick to them
Carb Refeeds Work by Boosting Leptin
Leptin is sometimes called the “satiation hormone,” but it’s probably more accurate to think of it as a starvation sensor.1 Its main role is to tell the brain whether we have sufficient energy on board, either in fat cells, which secrete leptin, or because we have recently eaten (especially carbs).
It’s well established that leptin levels drop both when we lose body fat and when we eat in a caloric deficit2 for even a short period. Remember, from an evolutionary perspective, weight loss signals that we are in a time of food insecurity and stress. Low leptin signals to the hypothalamus that we might be facing an energy shortage. In turn, the hypothalamus kicks on the processes collectively known as adaptive thermogenesis,3 or energy conservation. These include down-regulating thyroid activity and slowing metabolic rate, decreasing energy expenditure, and increasing hunger and appetite.
Premenopausal women’s bodies are especially sensitive to anything that sets off the “Danger! Starvation possible!” alarms. (Postmenopausal women are generally more resilient.) Leptin is a key player in that system. It is also involved in the regulation of insulin sensitivity and glucose metabolism, the female reproductive and immune systems, and skeletal and cardiovascular health. Basically, leptin is really important if we want to feel good and achieve optimal hormonal balance.
Leptin levels rise in response to eating carbohydrates specifically.4 Thus, one rationale behind carb refeeds is that by boosting leptin, we can reset the system. Basically, it tells the brain, “Hey, it’s cool, we have food around. It’s safe to let go of some of this body fat.”
Carb Refeeds Work by Relieving the Stress of Dieting
A related hypothesis is that dieting is physiologically stressful on the body. After periods of energy restriction, we see a decrease in thyroid hormones and an increase in cortisol (which may be related to falling leptin). These are part of the adaptive response that aims to restore energy balance. Carb refeeds alleviate the stress of being in a constant state of energy restriction.
Dieting Is Hard, and Carb Refeeds Help Us Stick to Them
One of the main reasons dieting hard is because of hormonal changes (ahem, leptin5) that increase hunger and appetite. Besides feeling unpleasant, this leads many dieters to eat more than they realize, undermining fat loss. Multiple studies also suggest that low leptin levels increase reward-seeking behavior. Basically, food becomes more appealing and harder to resist.
Low leptin is also related to depression6, anxiety, and perceived stress, all of which can make it harder to stick to your diet goals.
For all these reasons, periodically boosting your leptin via carb refeeds should make dieting feel less challenging. Beyond that, there’s also the psychological factor of knowing that you don’t have to strictly adhere to a diet indefinitely. Although it might seem counterintuitive, research confirms 78that giving yourself planned breaks can help relive the doldrums of dieting and actually increase your adherence in the long term.
Who Should and Should Not Consider Incorporating Carb Refeeds
There’s no evidence that carb refeeds are necessary or optimal if weight loss is your goal. Like so many things, this is going to be an n=1 situation. They might help, hurt, or be neutral depending on the individual.
First and foremost, if it ain’t broke, don’t fix it. If your current diet is working just fine, you feel great, and you’re losing weight, you don’t need carb refeeds. (By the way, if you’re impatient because you’re losing slowly, I haven’t seen any evidence that they will speed up weight loss.)
Likewise, they generally aren’t recommended for people who still carry a significant amount of body fat. There’s no real guidance as to what constitutes “significant amount,” unfortunately. As a rule, though, leaner individuals are more likely to benefit from the hit of leptin because they have less adipose tissue to produce it on a day-to-day basis.
DO: Reasons to experiment with carb refeeds include:
- You’re experiencing a weight loss plateau. This means several weeks of no change in weight or body measurements despite nothing else changing. This isn’t a guaranteed strategy, of course. There are lots of reasons weight loss can stall, not all of them related to leptin or diet adherence. It’s certainly worth a try, though.
- You’ve been low-carb and/or calorie restricted for a while, and you’re experiencing other signs of hormone dysregulation. These include menstrual irregularity and sleep9 disruptions, among others. Depending on how severe your symptoms, you might need more than the occasional carb refeed. For mild symptoms, an occasional refeed might help.
- You’re sick of dieting. Mixing it up with carb refeeds (which are not the same as “cheat days”) can relieve the dieting fatigue.
DON’T: Other instances when carb refeeds are not advised are:
- For people who are using low-carb or keto therapeutically, such as for epilepsy or Parkinson’s, unless advised by their health care practitioners.
- For people who are extremely insulin resistant.
How to Implement Carb Refeeds
No matter what strategy you use, you want to refeed with nutrient-dense, Primal-aligned foods. We’re talking sweet potatoes, potatoes, beets, baked goods made with almond or coconut flour if you want, in-season fruit, quinoa, maybe legumes if they work for you. If you want to eat some rice (sushi!), no judgement here.
Primal carb refeeds aren’t just an excuse to “cheat” (a term that I hate). You’ll see carb cycling protocols that allow, even advocate, eating copious amounts of junk food (another term I don’t love) on refeed days. Since our goal here is metabolic health and hormone balance, stick to the same Primal foods that support those goals, just with more carbs.
How Many Carbs Should I Add?
If you look at the literature on carb cycling, you’ll find various opinions. Depending on who you ask, it can be upwards of 300+ grams per day. Again, though, these come mostly from protocols aimed at physique and other athletes, and these high carb recommendations are for men who are already quite lean. It’s not clear how they apply to the average woman looking to kickstart their weight loss.
As usual, it’s also hard to find research on people who follow a low-carb Primal or paleo approach. In this oft-cited study,10 for example, the control diet was a mainly liquid diet supplemented with orange juice, yogurt, and cream that came in at an average of 224 grams of carbs per day. In the carb overfeeding condition, which was shown to boost leptin, the average daily carb intake was 394 grams—way more than the average Primal eater probably consumes.
In the absence of solid research-based recommendations, you’ll have to experiment. A good place to start is bumping up to twice your normal daily intake by adding nutrient-dense carbs to one or two of your meals, and increasing as necessary. If you want to be scientific about it, log your food and also keep track of metrics like weight, sleep, and energy. Play around with the frequency of carb-ups, as well as the amount of carb you add, and see what works best.
Should You Increase Carbs, Calories, or Both?
Technically, carb refeeds don’t have to involve more calories. Some protocols state that you should reduce fat on carb-up days so that your total caloric intake stays the same. Others specifically recommend adding carbs and increasing calories by a fixed amount.
Unfortunately, we don’t have enough studies to break down the separate effects of carbs and calories here. In theory, both should signal to the body that energy is available, but carb intake uniquely boosts leptin. Once again, experiment to see what works for you. To start, I’d recommend allowing your calories to increase on refeed days. You might dial back your fat a little, but I wouldn’t overthink it, especially if you’re already low-carb or keto. Adding 50 or 75 grams of carbs is 200 to 300 calories. That might be less than your typical caloric deficit. Even if you add more, it’s unlikely to negatively effect weight loss if we’re talking occasional refeeds.
I know that many dieters are afraid to increase their calories for fear of “undoing” their progress. That fear seems to be unfounded. Multiple studies confirm that intermittent dieting—mixing periods of caloric restriction with eating around your maintenance calories—is no worse11 for losing weight than continuous calorie restriction. It may even be advantageous12 for weight loss, and fat loss specifically.
How Often Should I Refeed?
In terms of how often to refeed, you have some options:
- Add in carbs whenever you plateau
- Carb cycling on a schedule
- Carb cycling around your menstrual cycle
- Eating carbs intuitively
Add in Carbs Whenever You Plateau
If you’re actively trying to lose weight, one option is to wait until you hit a plateau—at least a couple weeks when the scale stops moving—then add a day or two of higher-carb Primal meals to see if that moves the needle.
Carb Cycling on a Schedule
As I said up top, some carb cycling strategies involve fixed periods of lower- and higher-carb eating. Often this looks like eating low-carb during the week and then doing one or two higher-carb days on the weekend. This is more convenience than science though. There’s no reason you can’t do 9/1 or 12/2 or any other pattern that works for you. You don’t even need to take a whole day. Some people just do one high-carb meal per week and feel great.
Obviously this strategy is more of a lifestyle than an acute tool for breaking through a weight-loss plateau. This is for people who don’t do well with continuous dieting or who find it easier to stick to their goals when they have planned deviations. It is akin to the idea of a cyclical ketogenic diet, although you don’t have to be keto to use carb cycling.
Carb Cycling Around Your Menstrual Cycle
Another carb cycling strategy is timing carbs strategically around your menstrual cycle.
This strategy isn’t specifically geared at weight loss but rather supporting the whole hormonal system, but it potentially allows you to kill two birds with one stone. There are different approaches here, but a common one is increasing carbs 4 to 5 days post-ovulation (around days 19 and 20 of your cycle) and on the first couple days of your period. These are times when your leptin levels naturally dip, so you could possibly benefit from the boost. Some women prefer instead to add carbs around ovulation, days 13 to 15. Again, see what works be for you.
Eating Carbs Intuitively
Finally, you can wait until your body starts calling out for carbs and respond appropriately. In my opinion, intuitive eating is one of the goals of a Primal diet and lifestyle. When we improve hormone balance and tap into how good it feels to nourish ourselves with nutrient-dense foods, we should be able to trust when our inner voice says, “Hey, I could use some starchy vegetables here!”
Eating carbs intuitively isn’t the same responding to sugar cravings or eating something off plan just because it “sounds good.” I think we can all recognize the difference between listening to our bodies and eating purely for pleasure. (You’re more than welcome to do that too, but it’s not what we’re talking about here.)
Intuitive carb refeeds are probably going to work best for people who have been on the Primal train for a while and who generally feel pretty in tune with their bodies. Women who are dealing with chronic health issues or hormone imbalances might need something more structured.
Note that this is a different question than carb timing, which Mark covered recently. Carb timing is about when to eat your carbs during the day.
Don’t Be Afraid to Experiment
I’m a big fan of experimenting with your diet. There is so much bioindividuality, it’s impossible to find a one-size-fits-all approach. The best strategy for you is the one that hits that sweet spot where you to feel your best and also enjoy how you eat.
Moreover, I’m going to go out on a limb and say if you’ve been low-carb for so long that you’re afraid to consider eating even nutrient-dense, Primal-aligned carb-y foods like sweet potatoes, you should challenge yourself to try a carb refeed and see what happens. I’m not talking about people who know they feel better eating very-low-carb and simply don’t have the desire to switch it up. I’m talking about people who have a mental block around the very idea of carbs. We don’t want people to get “stuck” in a low-carb paradigm to the point where they feel unable to enjoy otherwise nutritious foods just because they have more carbs than, say, broccoli.
Finally, although their are good reasons to try carb refeeds if your current low-carb diet isn’t working the way you want, it’s only one of many things you might try. In particular, if you haven’t also gotten your sleep and stress in order, make those priorities as well. Carb refeeds can only do so much if you don’t have a solid foundation of healthy habits in place.
Tell us: Have you had success implementing a carb cycling approach? What works for you? What are your favorite foods to use to increase carb intake?
Related posts from Mark’s Daily Apple
The post Carb Refeeds for Women: Do They Help With Fat Loss? appeared first on Mark’s Daily Apple.
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Beyond the great debate about how many carbs we should be eating, there is another question you might be wondering about: When is the best time of day to eat carbs?
Today we’re going to dig into the data and see if we can get some answers. Before we do, though, I want to make something clear. The types and amounts of food you are eating are much more important than nutrient timing when it comes to health, body composition, and even athletic performance.
Before worrying about nutrient timing, you should:
- Eliminate the “big three”—grains, excess sugars, and offensive vegetable and seed oils
- Consume an appropriate amount of food for your goals and activity level—neither too much nor too little
- Ensure that you are getting enough micronutrients via diverse, nutrient-dense foods, plus supplementation when necessary
I’d also say that macronutrients—the relative amounts of carbs, protein, and fat you’re eating—comes before nutrient timing in the hierarchy of “likely to matter.” A Keto Reset is probably going to impact your health and body composition more than changing the timing of your carb intake.
Still, I know many of you are self-experimenters and optimizers. You like to explore ways to squeeze a little more “edge” out of your diet and lifestyle. For some of you, nutrient timing might be the key to resolving a nagging issue that hasn’t been fixed by diet and lifestyle changes. If this is something you’re curious about, read on.
The Best Time to Eat Carbs: Why Would Carb Timing Matter?
The growing field of “chrononutrition” investigates how food timing affects overall health. I’m sure you know that many bodily systems operate according to biological clocks. Sleep, immune system activity, and body temperature are all governed by circadian (~24-hour) clocks, for example. Disruption to our normal biological clocks negatively impacts health.
Metabolism operates according to circadian rhythms, too. On a basic level, we are meant to sleep when it’s dark, move and eat when it’s light. Insulin sensitivity and beta cell activity (the cells in the pancreas that produce insulin) are highest in the morning. Research shows that glucose tolerance—the body’s ability to clear glucose from the bloodstream after a meal—goes down if your sleep is poor or under conditions of circadian misalignment. There also seems to be a link between eating later at night, weight gain, impaired fat oxidation, and other negative health outcomes.
Taken together, this has led some researchers to suggest that we should eat most of our food earlier in the day to entrain, or align, our circadian rhythms. Doing so, they argue, could improve glycemic control (glucose regulation) and insulin sensitivity. It might also regulate appetite hormones and cortisol, and have downstream effects on body composition.
Carb Timing for Glycemic Control and Insulin Sensitivity
A number of studies seem to suggest that eating later is associated with impaired glucose tolerance and/or insulin sensitivity. On the other hand, both may be improved with early time restricted feeding (eTRF). This is where you eat in a compressed window, say 8 or 10 hours, and that window is shifted toward the morning. A typical eTRF schedule might entail eating all one’s food between 8 a.m. and 4 p.m.
Most of these studies focus on food timing generally, not nutrient timing per se. For example, in this study, men with type 2 diabetes ate all their calories in a 9-hour window. In one phase, they ate from 8 a.m. to 5 p.m. (eTRF). In the other, they ate from 12 p.m. to 9 p.m. Both schedules improved glucose tolerance, but only eTRF decreased fasting glucose.
A handful of studies do specifically look at carb timing:
- Healthy volunteers kept three-day food diaries. Those who ate relatively more of their food, and more carbs specifically, in the morning were also more insulin sensitive than late eaters. (Eating more fat in the evening was also correlated with poorer insulin sensitivity. It’s not clear how much these effects were driven by total caloric intake.)
- In another interesting study, researchers assigned men to eat two different diets for four weeks. They either ate most of their carbs before 1:30 p.m. and most of their fat after, or vice versa, in a cross-over design. For men who started out normal glucose control, carb timing didn’t matter. However, among men with high fasting glucose or impaired glucose tolerance, eating carbs at night led to unfavorable changes on several makers of glucose tolerance.
- In contrast, in this study, men followed a hypocaloric diet for eight weeks. Participants who were assigned to eat most of their carbs at lunch instead of dinner ended up with higher fasting glucose and insulin, and poorer insulin resistance.
Does type of carb matter?
Maybe. Researchers compared low-GI (glycemic index) and high-GI meals with most of the calories loaded into either the morning or the evening. Participants had the highest postprandial glucose (glucose after a meal) and insulin in the high-GI + evening eating condition. It didn’t matter when participants ate low-GI carbs. (Participants also consumed 302 grams of carbohydrate per day. Diets consisted of bran cereal, low-fat fruit yogurt, “fruit loaf,” and a Mars bar, among other things. It’s not clear exactly how these findings apply to Primal eaters.)
Conclusion: More research is needed in this area, but the available evidence points to morning carb consumption being favorable for glycemic control, perhaps especially among people who already struggle in this area.
Carb timing for athletes
As you know, I’m a big fan of athletes using fat for fuel. It’s an efficient, cleaner burning, more abundant source of energy. Once you become fat-adapted, it’s amazing what you can do as a fat-burner. As I detail in Primal Endurance, low-carb and keto diets work tremendously well for endurance athletes and even for hard-core strength athletes.
That said, there is no denying the ergogenic effect of carbs – carbs’ effect on stamina, physical performance and recovery. When you’re fat-adapted and running mainly on fat (and maybe ketones), adding some carbs to the mix can be like rocket fuel. I’m a fan of the “train low, race high” strategy for endurance athletes. Conduct most of your training using a low-carb approach, but add carbs strategically for your highest-intensity training sessions and races. You don’t need a lot, maybe 60-100 grams per hour.
Targeted Carbs: Should You Eat Carbs Before a Workout?
One strategy I’ve talked about before is targeting your carb intake around workouts. There are two rationales here. One is the aforementioned ergogenic effect — giving your workouts a boost. The second is that when you exercise, a glucose transporter in muscle cells called GLUT4 moves to the surface of the cell. This facilitates the transport of glucose into the cells without insulin.
Intense exercise also depletes glycogen, so there is a window after exercise in which ingested carbs are more likely to go to replenish glycogen. This is what I mean when I talk about the “glycogen suitcases being open” after exercise.
Thus, it makes sense to time your carb intake around exercise, especially hard and/or long bouts. In the keto world, this strategy is called “targeted keto.” The same principle applies for low-carb-but-not-keto folks. It’s not because you need the carbs for workouts—most of us do just fine without any special carb loading—but that’s when the body is most ready to use or store them.
Does Eating Carbs in the Evening Help You Build Muscle?
In the world of muscle gains, there are a handful of approaches that involve backloading carbs into the evening following a workout. Bill Lagakos does an excellent job unpacking them in a two part blog series here and here. Briefly, the logic behind carb backloading is that you don’t want to eat carbs when you’re more insulin sensitive in the morning because they’ll get stored as fat (oversimplifying here). Instead, wait until later in the day when insulin sensitivity decreases, then use exercise to push carbs into muscle instead of fat.
There’s no real evidence that this works, beyond anecdotal evidence from people who enjoy eating carbs at night. If you have body fat to lose, I think the evidence favors shifting calories and carbs toward the morning.
For the average person looking to gain strength and functional fitness, carb timing is not a great concern. For fitness competitors or people trying to push their physical limits, it might start to matter.
If you’re looking to gain lean muscle, you might find that ingesting a small amount of carbohydrate—25 to 30 grams—before hitting the gym can be beneficial. Contrary to popular belief, however, post-workout carbs do not seem to enhance muscle synthesis or recovery to a meaningful degree, especially not when protein needs are covered.
Bottom line: Carb timing isn’t important for muscle building except maybe for elite competitors and high-performers.
Timing Carbs for Weight Loss: What Does the Science Say?
In recent years, some people have claimed that eating carbs at night actually supports weight loss. In fact, this is one of the rationales offered for the aforementioned carb backloading. However, the studies they typically cite as evidence for this assertion have methodological problems that I can’t overlook.
Those studies are also at odds with a larger number of studies linking weight loss to eating more of your calories earlier in the day. Mechanistically, eating late delays the onset of the overnight fast, interfering with fat-burning and potentially with switching on ketosis. Eating later can also be associated with eating more, period.
Unfortunately for the purposes of this post, studies that look at meal timing and weight loss don’t examine nutrient timing, with one exception. In this study, researchers compared two diets, one prioritizing carbs at lunch and protein at dinner, and the other vice versa. Participants lost equal amounts of fat on each, but the group who ate most of their carbs at dinner also lost more lean tissue—not what you want! (This was also the study that showed poorer glycemic control with lunchtime carbs, in contrast to most other studies.)
Bottom line: When it comes to weight loss, there’s not enough data to convince me that carb timing seems very important.
Carbs Before Bed and Sleep Quality
Theoretically, carb intake at night could positively affect sleep by increasing tryptophan production, which is a precursor of serotonin, which in turn promotes sleep. It makes sense. No empirical research directly supports this hypothesis, though. Still, experts recommend you try adding some carbs at night if you’re struggling with sleep, especially on a low-carb diet.
There are plenty of studies looking at the relationship between macronutrients and sleep. However, they look at dietary composition as a whole, not nutrient timing. A single small study found that eating a high-GI meal four hours before bed improved sleep onset, compared to a lower-GI meal, and also compared to eating that same high-GI meal eaten one hour before bed. That’s all we have data-wise, besides anecdotes.
Conclusion: Anecdotal evidence aside, there’s no proof that timing carbs at night help your sleep. It probably doesn’t hurt to try.
So Where Does This Leave Us?
Well first, it leaves us asking for more studies that systematically investigate carb timing. I specifically want to see more studies looking at carb timing in a low-carb population. As usual, the studies I cited here involved a standard high-carb paradigm. If you read the reports and see what researchers are feeding their participants… well, let’s just say you Primal folks wouldn’t volunteer for these studies.
This always leaves me wondering how well any of these findings apply to us fat-adapted folks. We can’t know for sure.
Let’s summarize the findings we have, though. First, for entraining your circadian rhythm, improving glycemic control, and losing weight, the available data altogether point to the benefits of eating more of your carbs earlier in the day.
You might wonder how this fits with intermittent fasting. First of all, I.F., doesn’t have to mean skipping breakfast. Many people skip breakfast largely out of convenience. If it works for you, great. Nothing I’ve said suggests that it’s bad for you. That said, if you’re still struggling with glucose tolerance, or you have a few stubborn pounds of body fat you’d like to lose, loading more of your calories and carbs earlier in the day seems to be a worthwhile experiment, as I’ve said before.
It makes sense to target carbs around exercise, but it’s generally not necessary for athletic performance. Most weekend warriors can get by just fine without any special carb timing strategy. People looking to gain muscle may want to ingest a small amount of pre-workout carbs, and endurance athletes should be open to using carbs around heavy training and races. I still think becoming fat-adapted should be every athlete’s first priority.
Finally, maybe experiment with some extra nighttime carbs if you’re a low-carb eater whose sleep is suffering.
But Don’t Sweat It
Nothing I’ve seen suggests that carb timing is more important than the amount and quality of food you eat. Once you dial in those higher-priority goals, by all means go ahead and try being more intentional about your carb timing if you want.
It might make a difference if you’re at the top of your performance game looking to squeeze out a few more drops, or if you have lingering health issues. Otherwise, I’d consider it just another variable you can experiment with if you want, but don’t sweat it if you have bigger things to worry about.
More related posts from Mark’s Daily Apple
Challet, E. (2019). The circadian regulation of food intake. Nature Reviews Endocrinology, 15(7), 393–405.
Oda, H. (2015). Chrononutrition. Journal of Nutritional Science and Vitaminology, 61 Suppl, S92-94.
Oike, H., Oishi, K., & Kobori, M. (2014). Nutrients, Clock Genes, and Chrononutrition. Current Nutrition Reports, 3(3), 204–212.
Qian, J., Dalla Man, C., Morris, C. J., Cobelli, C., & Scheer, F. A. J. L. (2018). Differential effects of the circadian system and circadian misalignment on insulin sensitivity and insulin secretion in humans. Diabetes, Obesity and Metabolism, 20(10), 2481–2485.
Wefers, J., van Moorsel, D., Hansen, J., Connell, N. J., Havekes, B., Hoeks, J., van Marken Lichtenbelt, W. D., Duez, H., Phielix, E., Kalsbeek, A., Boekschoten, M. V., Hooiveld, G. J., Hesselink, M. K. C., Kersten, S., Staels, B., Scheer, F. A. J. L., & Schrauwen, P. (2018). Circadian misalignment induces fatty acid metabolism gene profiles and compromises insulin sensitivity in human skeletal muscle. Proceedings of the National Academy of Sciences of the United States of America, 115(30), 7789–7794.
Zilberter, T., & Zilberter, E. Y. (2014). Breakfast: To Skip or Not to Skip? Frontiers in Public Health, 2. Retrieved from https://www.frontiersin.org/articles/10.3389/fpubh.2014.00059/full.
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