Last blog reviewed the results of a recent study which has been the subject of extensive media coverage. The study was designed to show that high insulin levels generated by high carbohydrate consumption, may increase the conversion of food into fat storage. The study showed, following a period of weight loss, that subjects consuming a low carb diet, consisting of 20% carb, 20% protein and 60% fat, burn more calories per day. There were, however, a number of caveats associated with the results. The major one was that the protocol used was too expensive, impractical and difficult to implement to be incorporated into the daily lifestyle of individuals trying to lose weight.
The obvious question is what these results mean to serious endurance athletes who are trying to improve performance and maintain an ideal weight. Is insulin the good guy or the bad guy? The media and the internet love to demonize sugar and insulin but it is important to recognize that insulin has a multiplicity of effects and that your body uses the same macro-nutrient differently depending on both timing and need. This should not be surprising. Most endurance athletes realize importance of recovery nutrition, the period 45 minutes after exercise. During the “recovery window” insulin is not the bad guy, rather it is the hero.
Although insulin facilitates fat storage, it also has powerful anabolic effects which are essential to the endurance athlete. Insulin stimulates protein synthesis via a number of mechanisms, slows protein degradation and serves as the stimulus for the replenishment of glycogen stores depleted after exercise. Carbohydrate and insulin are essential during muscle recovery and the benefits are magnified when carbohydrate is combined with protein in a 4 to 1 ratio. Similarly, during exercise a low carb diet is detrimental to endurance performance. During moderate to intense exercise, high glycemic carbs or simple sugars serve as an immediate source of fuel for working muscles. Studies have shown low carb sports drinks are not as effective in extending endurance as sports drinks containing 6-8% carbohydrate.
The bottom line - low carb sports drinks should not consumed during and in the 45 minutes post exercise especially during moderate to intense exercise lasting more than 45 minutes.