High-protein diets are a popular method of weight loss. You increase your intake of protein and fat while reducing your carbohydrate consumption to encourage a metabolic change within the body that causes a greater loss of weight. But this metabolic change, coupled with the carbohydrate restriction, can sometimes lead to undesirable side effects, including fatigue.
Diets high in protein tend to limit your intake of carbohydrates. Even nutrient-rich foods like fruits, vegetables and whole grains are restricted to a fraction of their recommended daily intake. This lack of carbs causes ketosis, a metabolic change that forces the body to turn to stored fat for energy, the National Institute of Diabetes and Digestive and Kidney Diseases explains. As the body breaks down fat, you lose weight.
This weight loss, however, can come at a cost. Carbohydrates are the body's main source of energy. Eating too few fruits, vegetables and whole grains can leave you feeling weak and tired, warns the NIDDK. Compounding the problem is ketosis, which is also known to result in fatigue as well as a loss of potassium. And according to the Mayo Clinic, if potassium levels drop below 3.5 milliequivalents per liter, you can begin to suffer from weakness and fatigue. All of these factors can contribute to feelings of extreme fatigue.
Most people eat roughly 300 or more grams of carbohydrates a day. High-protein diets limit your daily intake of carbs to anywhere between 15 and 60 g. As soon as you drop your carbohydrate consumption below 130 g, your body goes into ketosis, explains the NIDDK. It's at this time that you may begin to manifest symptoms of the metabolic change, including weakness and fatigue.
Increasing your intake of complex carbohydrates, like fruits, vegetables and whole grains, can often combat these feelings of weakness and fatigue. Many medical professionals endorse diets containing up to 15 percent protein, 60 percent carbohydrates and 25 to 35 percent fat to promote a healthy weight loss, according to Vanderbilt University.
Before starting any weight-loss program, talk to your doctor. Though diets high in protein are often considered safe, especially in the short-term, your health may require other dietary modifications to promote a healthy loss in weight.