The keto diet has exploded in popularity in recent years, and for good reason: cutting carbs is one of the best ways to cut fat, period. The additional benefits, like improving insulin sensitivity, reducing inflammation, curbing appetite and reducing cravings, and even reducing the frequency of seizures, are also nothing to shake a stick at. However, there are some reported negative effects of being on a keto diet long term that deserve attention, like fatigue and stalled performance or weight loss. If you’re experiencing these, keep reading, because we’re breaking down why a full-time keto diet might not be the most efficient for you, but how you can still get the benefits of a keto diet while introducing more carbs.

Benefits of the Keto Diet

Before we go into the reasons why you might want to avoid going keto full-time, let me just say that this isn’t a bash against low carb diets. Plain and simple: they work, I use them, and their benefits are amazing. A quick cap on why keto is great:

1. Helps You Cut Fat Fast and Lose Weight

Dropping carbs is one of the easiest ways to shed extra pounds. In fact, it’s been shown that people who restrict carbs often lose 2-3 times more weight as regular dieters, without increased hunger. [*] This happens for a variety of reasons, the first being that reducing carbs causes your body to rapidly flush water, as carbohydrate molecules hold more water in your body (this also makes carb restriction great for cutting quickly). However, reducing carbs also reduces insulin levels, which causes your body to store less fat. It also forces your body to burn fat for energy, since its normal source of glucose (carbs) is no longer available. This puts you directly into the coveted “fat-burning mode” you’ve probably heard about when people talk about keto and low-carb diets. To add icing on the cake, studies show it also significantly reduces your appetite, so you’re not tempted to nosh on extra calories that can stall weight loss. [*]

2. Can Reduce Inflammation

Inflammation is at the root of many diseases, and can even be a problem after workout injuries, causing swelling and joint pain. Research shows low carb and keto diets can help reduce chronic inflammation, which could also help reduce the pain stemming from it. [*]

3. Can Boost Energy

Excusing the quick trip back to high school biology, remember how our cells contain oblong structures called mitochondria? These are the energy-producers of our cells, and restricting carbs has been shown to help our brains create more of them. [*] More mitochondria potenially equals more energy production, and may be one of the reasons why people feel an initial energy boost when they go keto.

Pitfalls of an Extended Keto Diet

With all of that being said, for some people, keeping carbs below 50 grams a day long-term can cause a few serious issues. Depending on how much body fat you have to lose, or how your metabolism and thyroid health is before you start, these negative effects may take 6 months to a year to show up. However, plenty of studies have shown keeping carbs low can do a number on your body eventually.

1. Can Disrupt Gut Bacteria

Some long-term studies have shown being on the keto diet can damage the composition of bacteria in your gut, increasing markers for inflammation. Researchers believe this is due to eating so much fat and not as many varied plant foods that feed your good gut bacteria. [*] While this may not seem like a huge deal, it can not only disturb your digestion, but also lower your immune system, since these good bacteria serve as a first line of “defense” against invading viruses and other bugs.

2. Can Cause Fatigue

While many people become “fat adapted” on keto diets, meaning they’re burning fat for energy instead of glucose, some (especially athletes) may find their energy levels dipping from restricting carbs for too long. This is especially true when we’re talking intense training 4-5 times a week. Some studies have shown athletes on long-term keto diets tend to perform poorer on anaerobic exercises than athletes who ate more carbs. [*] Again, everyone is different and some people thrive staying on keto long-term, but if your weight loss or performance has stalled and you’re feeling run-down, sticking to low-carb for too long could be the culprit.

3. Can Interfere With Thyroid Function

Our thyroid hormones play a huge role in regulating metabolism. Some studies show that low carb diets can cause a drop in thyroid hormone. [*] While this doesn’t necessarily mean that your thyroid is being harmed by a keto diet, it simply means it can put additional stress on your body if carried on for too long, or if your body is already under a ton of stress from training or lifestyle. Low carb diets can also increase cortisol, the “stress hormone,” which can put a strain on your adrenals, leading to fatigue. [*]

Cyclical Ketosis: The Better Option

Obviously, myself and other athletes frequently eat low carb or keto to cut weight, and the extra good fats can provide an amazing source of steady-burning energy. Plus, the other benefits of the keto diet, like reduced inflammation and appetite, are something we’d all like to cash in on. However, if your energy levels are consistently low or you’re having trouble putting on muscle or improving performance, you might want to consider cyclical keto, or “carb-cycling.” Cyclical keto essentially involves rotating in and out of ketosis by have carb “refeed” days, which can help stimulate thyroid hormones and offset the potential negative effects of long-term keto. Some people doing carb cycling mention better sleep and improved performance by cyclically introducing more carbs. In essence, by sporadically introducing more carbs, you get the best of both dieting worlds. The easiest way to try cyclical ketosis is to have a carb refeed day once or twice a week, upping your carbs to around 150 grams, then dropping them back to keto levels for the rest of the week. The key is not to binge on crappy carbs (you know what they are) or sugar, but whole-food carb sources that can also replenish minerals, like sweet potatoes, beets, squash, carrots, and other starchy roots and veggies. Try doing this for a couple weeks and see how you feel energy and performance-wise.

Just a quick mention for you for your keto or low carb days, if you’re getting bored flavor-wise: I use Flavor Republic to season my meals, and the variety of flavors really helps curb cravings and make meals more satisfying. As I said, I regularly watch my carb intake, especially when I need to cut, and Flavor Republic is my lifesaver. Have you tried introducing carb refeed days during keto? How did it work for you? Leave a comment below with your experience.