There are many benefits to a low-carb diet:
You can lose fat ASAP.
You can restore insulin sensitivity and lower blood sugar levels for less diabetes risk.
You can improve your body’s ability to burn fat as a fuel source.
You can reduce appetite and decrease food cravings.
You can take control over what you’re eating.
You can lower your blood pressure and decrease heart disease risk.
Despite all these benefits, low-carb isn’t always the best option. Some people feel like they are being suffocated by carbohydrate restriction. The idea of not being able to eat bread for the foreseeable future seems like a fate worse than death. For others, the high-octane nature of their lives makes low-carb a bad choice that can send them into a miserable spiral of unbalanced hormones.
Then there are athletes. Although some endurance athletes have recently gotten superior results from low-carb diets, athletes in sports with a high-intensity component aren’t going to have the high rate of energy production to sustain maximal performance on a low-carb diet.
Therefore, this article will give you a heads up about situations in which a low-carb diet is a bad idea, with pointers on what to try instead.
#1: High Cortisol/Excess Stress
When you live a high-stress lifestyle, whether it’s because you have a challenging job, family struggles, or you’re burning the candle at both ends, your body will constantly be pumping out cortisol in an effort to help you cope with the stress.
Cortisol is a stress hormone that helps you feel alert and awake. It follows a natural rhythm such that you experience a large elevation early in the morning to help get you out of bed and then it follows a curve that slopes downward over the course of the day.
One effect of cortisol is to release stored energy and provide glucose to keep you going when you haven’t eaten recently. For this reason, you typically experience elevations in cortisol right before meals to coincide with the natural decrease in blood glucose.
On a low-carb diet, blood sugar levels drop, which can be great for resetting insulin sensitivity, but it is not so good for minimizing that cortisol spike. In fact, the lack of carbs can lead to a significant increase in your 24-hour cortisol readings and a large upward shift in your daily cortisol curve. Anyone with a healthy cortisol curve will be able to handle the shift, but if you’re feeling overwhelmed, a low-carb diet is likely to exacerbate the problem by increasing the amount of cortisol that is being secreted.
This can have a number of negative side effects:
Too much cortisol leads to inflammation, which is associated with increased storage of visceral belly fat.
Elevated cortisol triggers cravings for high-carb foods. Cortisol is an insulin antagonist, meaning that when insulin is released, cortisol drops. Carb cravings are the body’s way of protecting you from high cortisol and stress.
Elevated cortisol degrades tissue and compromises body composition by leading to the loss of lean muscle mass.
The Bottom Line: If stress is getting you down, a very low-carb diet is unlikely to give you the best results. Instead a moderate carb intake in the range of 150 grams a day from a variety of whole sources is generally recommended. Lower carb foods from vegetables and berries and higher carb foods like grains, beans, nuts, seeds, and fruits can be included. Naturally, individual needs will vary depending on whether you’re actively trying to lose fat or just want to create some sanity with your eating and in your life.
Of course, it’s recommended that you generally steer clear of refined carbs, but if this feels like a death sentence, then making it a goal to limit these foods to less than 20 percent of your carbs is a good start.
Carb timing can be a useful approach for people who are trying to balance cortisol. Most people find they get best results by starting the day with a high-protein, low-carb breakfast, and then gradually increase carb intake over the course of the day. Save your highest carb meal for dinner to promote relaxation and deeper sleep. Also be sure to always pair higher carb meals with protein to slow digestion and reduce blood sugar spikes.
Whether they are used during training or consumed as part of the diet, carbohydrates are an impressive performance-enhancing tool for athletes. They allow most athletes to feel and perform better than on lower carb diets.
Carbs can also accelerate recovery from hard training. When you exercise intensely, the body produces reactive oxygen species, which the insulin spike you get from high-carb foods can help suppress. Consuming carbs will also replenish glycogen stores and help the body clear cortisol released during exercise.
Does this mean that a high-carb intake is a necessity for all athletes?
Not necessarily. Studies show low-carb ketogenic diets that supply less than 50 grams a day can be useful for athletes who need to reduce body fat because the high protein intake allows them to sustain muscle mass while reducing calories. Additionally, a lower carb intake requires the body to increase enzyme levels involved in fat oxidation so that the body is able to use fat stores for energy during longer duration exercise.
Additionally, it should be noted that for people who are exercising for fat loss, or even those who are doing moderate intensity exercise, a high-carb intake is not necessary. There’s nothing wrong with training in a low glycogen state and doing so will increase fat burning and improve your body’s metabolism.
For clarity, studies show that a higher carb intake is most beneficial in the following situations:
When training twice-a-day or doing multi-day competitions, a higher carb diet is beneficial for rapidly replenishing glycogen fuel stores.
When training for high-intensity sports such as basketball or combat sports, a higher carb intake will allow for the higher rate of energy production necessary to sustain performance.
For precision sports, such as gymnastics, a higher carb intake can activate central nervous system drive to the brain for better focus and explosive output.
The Bottom Line: Unless you are training at a high-intensity twice a day, you can generally fulfill their carb needs from food—preferably whole carbs such as fruit, grains, and starchy vegetables. That said, a superstarch such as UCAN, may be beneficial around training to sustain blood sugar and support the body’s ability to adapt to the biochemical requirements for peak performance.
Many athletes wonder about the wisdom of using simple, refined carb foods such as bread, pasta, and sweets either per-workout or during recovery. Although they may be useful for fast glycogen replenishment, they are not recommended due to the fact that they wreck havoc on blood sugar and are nutritionally empty. Favoring whole, plant-based carbs is a better choice since these foods have a protective effect, helping the body clear waste products for faster repair of damaged tissue and less muscle soreness.
For example, the anthocyanins in berries and grapes counter muscle soreness after exercise, whereas pineapple has nutrients that support enzymatic function to restore cellular activity. Root vegetables (sweet potatoes) and cruciferous veggies (broccoli) provide high levels of vitamins to aid recovery. Finally, cooked grains and beans are more energy dense and will induce a larger insulin release to promote an anabolic environment in the post-workout period.
#3: Low Thyroid Hormone
If you suffer from an underactive thyroid (called hypothyroidism), a low-carb diet is probably not the way to go. There are two forms of thyroid hormone—one active and one inactive—that regulate metabolic rate by affecting enzyme activity, body temperature, and influencing energy levels.
The main reason why carb intake affects thyroid function is that insulin is needed for the conversion of the inactive T4 hormone into the active T3 hormone, and insulin is generally quite low on very low-carb diets. The drop in insulin from lack of carbs is great if you’re suffering from insulin resistance or are at risk of diabetes, but it can cause problems if you’ve already got low thyroid hormone levels.
Therefore, a moderate carb intake is generally a better choice if you have hypothyroidism. One option is to try carb cycling in which you generally eat a lower carb diet with regular higher carb meals every few days. In fact, this is a standard way for people to avoid the natural drop in thyroid hormone that coincides with a low-carb diet designed to reduce body fat. For example, try eating a high-carb, high-calorie every 5 to 7 days when on a low-carb fat loss diet because this will stimulate insulin and give your thyroid a lift.
The Bottom Line: If low thyroid activity is an issue for you, it’s recommended you work with a doctor or nutritionist to establish the optimal carb intake. It’s possible that a low-carb diet with regular higher carb meals will do the trick, whereas in other cases, a more higher daily carb intake will be a better fit.
#4: Gastrointestinal Problems
A low-carb diet is naturally a higher protein diet. Although there are some great things about high-protein foods, such as the fact that they are very satiating and are used by the body to repair damaged tissue instead of being stored as fat, one drawback is that they often lead to inflammation in the GI tract.
The bacteria in the gut live off what you eat. If animal protein reaches the GI tract without being fully digested it will fuel the proliferation of inflammatory bacteria, which is associated with increased disease risk over the long-term. A related problem is that when people eat low-carb, they tend to get less indigestible fiber. Fiber is essential for GI health, promoting the survival of protective anti-inflammatory bacteria that support optimal body composition.
We can see this in practice with a Tufts University study that found that people who had more lean muscle mass due to a higher protein intake had higher levels of biomarkers of inflammatory gut metabolism. These markers are linked with adverse health conditions, including gastric cancer, obesity, and type II diabetes. The Tufts researchers suggest that although a high dietary protein intake is important for the optimization of muscle mass, it will lead to the growth of dangerous inflammatory gut bacteria, especially when high-fiber foods are lacking.
One solution to this problem is to support the growth of beneficial anti-inflammatory gut bacteria with a diet high in indigestible fiber. If you’re eating very low-carb (below 50 grams a day), you’ll probably need to save all your carbs for low-carb vegetables such as leafy greens, broccoli, cauliflower, green beans, peppers, and squash.
You’ll also need to get some resistant starch in your diet, which can be gotten from foods like bananas, oats, and potatoes, however, these are all higher in carbs. Therefore, shooting for a moderate carb diet in the 100 to 150 grams a day range may be a better option, or you can supplement with raw unmodified potato starch, which provides indigestible carbohydrates, so they don’t count toward your overall carb total.
The Bottom Line: If you’re suffering from GI problems, a conventional low-carb diet such as Atkins probably isn’t the way to go because it simply won’t provide the fiber necessary for healthy GI function. Most people will have better results from a well-designed moderate-carb intake that provides plenty of indigestible fiber from vegetables, fruit, and select grains. Taking potato starch may also help to improve gut flora and achieve success with a lower carb intake.