At the onset of the diet, performance may become less than optimal. However, research has found that over time, these performance decrements disappear . Some studies, including those conducted in our lab, have even found that people following a ketogenic diet and resistance training can gain the same amount of strength compared to people eating high carbohydrate diets.
Research suggests that keeping protein to around 1.2-1.6 grams per kilogram of body weight allows individuals to maintain or gain lean mass. Even among individuals in a calorie-restricted state, studies have found fat loss to be as high as 95 percent of total weight lost on a ketogenic diet, and consuming a ketogenic diet at maintenance calories leads to increases in muscle mass. The positive effects on muscle mass are due in part to the protein sparing and anabolic effects of ketones.
Targeted ketogenic dieting involves incorporating carbohydrates around a training session (before, during, and/or after). By doing so, the adrenaline from the training session blunts the insulin response you would get from the carbohydrates (thereby preventing the negative, anti-ketogenic effects of eating carbs) but could potentially give you an acute cognitive effect . No studies have looked directly at a TKD, but individuals who are training hard have reported great benefits with this type of approach. Keep in mind that your particular goal (fat loss, muscle gain, performance, etc.) will determine what is optimal for you.
Regardless, we do not recommend attempting a TKD until you are thoroughly keto-adapted, and then we suggest that you start by experimenting with consuming a small amount of carbohydrates before, during, and/or after your workout (i.e less than 30 grams).
Studies suggest that the body does not require carbohydrates to replenish glycogen , and research in keto-adapted athletes has found that they spare and replenish muscle glycogen at similar rates as carbohydrate-adapted athletes . At the beginning of a ketogenic diet, as your body is adapting to burning fat, glycogen stores may be limited, but they soon rebound once you’re fully adapted.
There are plenty of studies demonstrating improvements in body composition (i.e., reduced fat mass and maintained or increased lean muscle mass) and blood lipids (i.e., reduced triglyceride and total cholesterol levels and increased HDL cholesterol levels) on a ketogenic diet without exercise . However, exercise is a key component of a healthy lifestyle and can dramatically improve your results on a ketogenic diet. For this reason, we highly recommend some type of physical activity or exercise on a ketogenic diet, even if it is just walking ten thousand steps per day (about 5 miles). Additionally, research shows that even moderate walking increased brain ketone uptake so get get out and move.
Any exercise is better than no exercise! However, we have found in our lab that training at a high intensity can increase the production of ketones. So train hard and try to incorporate resistance training with some type of cardio, even if that cardio just is going on a walk after each meal.
In most cases, a carbohydrate refeed is not necessary on a ketogenic diet, as the keto-adapted biological and metabolic changes do not require dietary carbohydrates. There are certain circumstances, however, in which an increase in small carbohydrate influx may be beneficial (i.e. high intensity activity/sports or even during a menstrual cycle for females); however, more research is needed on this topic, specifically with respect to variations of ketogenic diet including “cyclic” and “targeted” ketogenic diets.