The “Keto” diet has been attention grabbing headlines for the past few years. Weight loss diets that are low carbohydrates and high protein have been mainstream as the “go-to” diet. The keto diet is different in that unlike most low-carbohydrate diets, which focus on protein, the keto diet is focused on high fat. Generally the primary source of energy for our bodies is carbohydrates. However, there is an alternative fuel source that is more efficient for our body which is ketones. Ketones are formed when the body breaks down fat in the liver. Ketones are naturally made by the body after fasting for 16 hours. Ketosis is the state of having elevated ketone levels above 0.5 millimole per liter (mmol/L). By lowering the amount of glucose taken in from food and the amount of glucose stored as glycogen, the body is able to start burning fat/ketones as its primary fuel source. At the onset of a keto diet, performance in athletics may decline, but should improve 6 weeks after. Even if people are aren’t necessarily exercising, body composition has been shown to improve on a ketogenic diet (Volek et al., 2010). Lean muscle increases and body fat decreases.
In regards to weight loss, a ketogenic diet results in more weight loss than low-fat diets. For example, in one study, after six months, weight loss was greater among those following a ketogenic diet than those following a low fat diet (Hession et al., 2009). The ketogenic diet can be easier to incorporate into a more permanent lifestyle change than a low-fat diet because of its satiating effects and the resulting decrease in hunger. Before starting a ketogenic diet, however, it is important to speak with your primary care physician to see if this diet is right for you.