If you’ve been following a low carb diet for a while and have been experiencing weight loss plateaus, hormone imbalances, low energy, or a decline in athletic performance, you might want to consider implementing strategic carbohydrate refeeds.
A carb refeed is an intentional increase in carbohydrate consumption, often done on a periodic basis such as daily or weekly. Keep reading to learn how carb refeeds can help you minimize potential negative hormonal or metabolic effects from long term low carbohydrate intake.
Why Carb Refeeds Are Important
Carbohydrates and Insulin
We know that carbs have an impact on the hormone insulin. And when our bodies don’t respond properly to insulin, we increase our risk for disease (metabolic syndrome, type II diabetes, heart disease, non-alcoholic fatty liver disease, Alzheimer’s, and more).
Insulin is responsible for telling our cells (mostly muscle, liver, and fat cells) to soak up sugar from the bloodstream. If your cells don’t respond, the level of sugar in your blood remains high and can begin to have toxic effects. This is called “insulin resistance”.
One way we can become resistant to insulin is from eating carbohydrate-rich foods in excess, especially from refined, heavily processed sources. These foods result in excess glucose in the blood, leading to chronically elevated blood sugar and cells that eventually become resistance to insulin signalling. Chronically elevated blood sugar is a serious problem in and of itself, but so is becoming resistant to insulin, as it serves many important functions in the body.
Insulin Isn’t All Bad
Just because insulin resistance sucks doesn’t mean we should immediately demonize insulin. Insulin is talking to so many more things than just muscle, liver, and fat cells. It’s also a signaling hormone for many other systems in the body:
- Thyroid: Up-regulating enzymes that stimulates beneficial thyroid hormone conversions
- Bones: Modulating osteoblast activity to promote bone growth
- Brain: Binding to brain cell receptors to help regulate hunger, adiposity, neuro-inflammation, and some cognitive functions
- Hormones: Balancing estrogen and testosterone levels, interacting with cortisol, growth hormone, dopamine, serotonin, and many others
- Immune system: Enhancing neutrophil, macrophage, T cell, and natural killer cell activity
As you can see, insulin is not merely a fat storage hormone. It has many other important functions in the body, which means it's important to keep cells responsive or sensitive to insulin.
Optimal insulin sensitivity can be achieved by eating the right amount and right type of carbohydrates at the right time. Sounds simple, but there’s a ton of individuality involved. Especially when it comes to very low carb diets.
What Happens on a Very Low Carb Diet?
Low carb diets have shown promise to be beneficial for weight management, type II diabetes, and neurological disorders. This is, in some part, likely due to the restriction of carbohydrates and the ensuing positive effect on lowering blood sugar levels.
However, one of the drawbacks of a long term, very low carb diet is that insulin levels can be chronically low. In the absence of carbohydrates, little to no insulin is secreted, which can actually cause cells to become resistant to insulin signalling in the very same way that too many carbohydrates can!
In other words, chronically high AND low insulin levels can have similar negative effects on our health. It’s a Goldilocks hormone, and the goal is to strike a balance of optimal insulin sensitivity.
Leptin is another important hormone in this puzzle. It’s released by fat cells and communicates to your brain how much fat (i.e. stored energy) you have. Your brain recognizes higher leptin levels as an indicator that you don’t need to worry about food. Low levels tell it that you are running low on energy resources, so it responds by trying to get you to save more energy. What you may feel from this are food cravings (especially for calorie dense food), mood swings, less energy, and plateaued fat loss efforts.
When moving to a low carb diet also coincides with consuming less calories, we see a decrease in leptin levels and the accompanying side effects from above. That’s the bad news. But the good news is that an increase in carb intake has been shown to boost leptin levels and alleviate the negative symptoms associated.
In summary, while very low carb diets can have positive effects on insulin and leptin signalling initially, when done to an extreme without adequate carbohydrate refeeds, the benefits may backfire.
Signs You Might Need to Implement Carb Refeeds
Carbs and Physical Performance
Carbs are needed for optimal high-intensity performance. They provide the fuel for your muscles in the form of glycogen. Long term low carb dieting can lead to depleted glycogen in muscles/liver and a hindered ability to perform high intensity, glycogen-demanding exercise.
In the endurance community, on the other hand, there’s a notion that very low carb, or ketogenic diets can lead to superior endurance performance due to their ability to make folks more efficient at using fat for energy. While studies support the claim that very low carb diets increase fat oxidation, they have not demonstrated any performance benefits.
One diet strategy that has been shown to actually increase endurance is the “train-high, sleep-low” method, where athletes switch between periods of low and high carb intake. The aim is to maintain the ability to efficiently use both carbs and fats for energy, referred to as “metabolic flexibility.” Not only does this ability reduce risk of disease, it also improves performance.
In other words, properly timed carbohydrate refeeds can be an effective strategy for optimizing athletic performance and maintaining metabolic flexibility when following a low carb diet.
Weight Loss Plateaus
Trying to lose the last few pounds of fat, but seeing progress stall? It’s not uncommon to see significant weight loss in the first week or two of a low carb diet, but then start to plateau. Coincidentally, it’s shown that 1 week is all it takes to see a drop in leptin levels.
If you’re close to your fat loss goal and have reached a plateau, a carb refeed can give you a hormonal boost needed to shed the last few pounds. This assumes you are adequately sensitive to your own insulin and leptin hormones. (However, if you’re farther away from a healthy weight and/or have signs of being resistant to insulin and leptin, you may not respond as well to a carb refeed.)
Hypothyroid or Adrenal Dysfunction
We know insulin plays an important role in thyroid hormone production, and it would be unwise for someone with a known thyroid condition to stay too low carb for too long. If you’re experiencing some symptoms of hypothyroidism (hair loss, cold hands/feet, low energy) on a prolonged low carb diet, you might see some improvement by adding carbs back into your diet.
Additionally, very low carb diets are associated with higher cortisol levels. If you’re someone already dealing with a lot of stress in other areas of life or have signs of adrenal dysfunction, the added stress of a low carb diet may not be the best choice.
How to Do a Carb Refeed
There are many ways to do a carb refeed, and depending on your situation one may be better than another. Each method involves a large spike in carbohydrate intake at a scheduled time, but the size and frequency will vary based on individual activity levels, genetics, biomarkers, and so on.
Here are a few common methods you can experiment with to see what works for you:
- Best For: Individuals who engage in lower amounts of physical activity, and are seeking the health benefits of a low carbohydrate diet but want to avoid negative long-term effects.
- How to Do It: Pick one day or one meal per week to eat a larger amount of carbohydrates. For example, your refeed could be on a weekend or on your most physically-active day.
- Recommended Amount of Carbs: 100-300g carbs, depending on the individual.
- Best For: Individuals that perform a few intense training sessions (heavy resistance training or HIIT) each week and want to optimize performance and recovery, while maintaining ideal body composition.
- How to Do It: On big training days, increase your normal amount of carbohydrates in your first meal post-workout.
- Recommended Amount of Carbs: 50-150g carbs, depending on the individual.
- Best For: Serious athletes who train nearly every day or multiple times per day who need to enhance recovery between sessions.
- How to Do It: Pick a meal to consume a larger amount of carbs. Most often this is post-workout at dinner.
- Recommended Amount of Carbs: 50-200g carbs, depending on the individual.
Determining Your Ideal Amount of Carbs
If you want to make an educated guess on whether or not you’re better off on the low or the high end of these ranges, you can look at your ancestry. If your ancestors’ traditional diet was high in carbohydrates, it’s likely you will respond better to more carbs. If they had a lower carbohydrate diet, you may respond better to fewer carbs. This article on Mark’s Daily Apple has great tips for dialing in your diet based on your ancestry and genetic profile.
Given that the same carbs can have completely different effects on different people, some self-experimentation might be needed for the best results. One easy way is to take detailed notes of how you feel with different carb amounts like this.
Alternatively, you can go straight to the source and use a glucometer to measure your blood sugar response to different amounts and types of carbs, as outlined by Robb Wolf in the 7-Day Carb Test from his book “Wired to Eat.”
Worst Sources of Carbohydrates
When choosing where to get carbs for your refeed, some sources are better than others. Refined carbohydrates, stripped of their fiber and micronutrients, tend to cause a greater spike in blood sugar compared to their whole food, fiber-rich counterparts. This spike and the ensuing crash can wreck energy levels. Additionally, refined carbs have been shown to promote overeating and weight gain, alter your gut biome, and damage your intestinal barrier. No thank you.
Here are some carb sources that you’d be better off avoiding during refeeds:
- White bread
- Sugar-sweetened beverages
- Most packaged foods — check the ingredients!
Best Sources of Carbohydrates
A good carb choice is going to be one that replenishes glycogen, balances insulin sensitivity, and also provides valuable nutrients. Unrefined, complex carbohydrates from whole-food sources are going to be your best bet for getting the most out of your carb refeed.
Here are some of the best carb sources for a refeed:
- Starchy vegetables like potatoes, squash, yams, etc.
- Properly prepared grains like white rice, quinoa, oats, etc.
- Whole fruits
- Nutritive sweeteners such as honey, maple syrup, or blackstrap molasses
Whole foods like these are ideal, but sometimes life gets in the way. In a pinch, there are plenty of more convenient and portable options, usually in the form of a packaged meal or energy bar. However, you’ll want to be a bit selective, because as it turns out, not all energy bars are created equal. Pick one up and check the ingredients list — is it full of actual foods or does it look like the glossary of a chemistry textbook?
Kion makes a clean energy bar that we think is pretty rad and certainly passes all these tests. If you’re looking for something easy for a refeed that also includes whole, nutritious ingredients like honey, quinoa, almonds, cacao, and coconut, we’ve got you covered.
Carb refeeds can be a valuable tool if used appropriately. There are several options, from once a day to once a week, but some experimentation will be necessary for determining the exact method that works best for you.
Some of the benefits you may start to see after strategically including more carbs in your diet include:
- Balanced hormones
- Better body composition
- Enhanced athletic performance and faster recovery
- Increased energy
- Reduced cravings
- More restful sleep
Not sure where to start? A safe bet for any refeed is after an intense workout. Aim to have an extra serving of a natural carb source post-workout to naturally replenish glycogen stores. And if you don’t have access to your own kitchen, you can always chuck a few Kion bars in your gym bag!