Amped Training

In general many find that they do better, in terms of adherence and cravings, on low carb diets. However those engaged in large amounts of endurance activity, or even those that simply do better on higher carb intakes, may find they need the carbs to support their training.

Carbs, as I mentioned before, will ultimately end up as glucose in the bloodstream, available for uptake by cells for use as energy. This process is often linked to the hormone insulin, which is considered a “storage” signal as it is linked to the processes by which cells take in nutrients.

Insulin causes an upregulation of the molecules responsible for glucose uptake, as well as other related pathways. Because of its nature as an energy-providing hormone, it tends to also signal anabolic/growth processes as well. However, cells have also demonstrated the capacity for nutrient uptake without the presence of insulin, so it is not the complete picture.

For all intents and purposes, the two tissues you're most concerned with are going to be muscle and adipose (fat). How these tissues respond to insulin is determined by a quality called insulin sensitivity. Insulin-sensitive tissues require less insulin to exert a given effect than in more insulin resistant tissues.

In an ideal situation, you'd have high insulin sensitivity in your muscle tissue, and high insulin resistance in your body fat. Unfortunately, this is genetically determined and not something you'll have any control over, barring a few exceptions (one of these being drugs).

Broadly speaking, this controls another aspect of nutrition called partitioning. This is “what goes where”, meaning that it's a ratio between nutrients that are diverted to muscle (and other essential functions) vs. those diverted to fat tissue. As with the above, there's little short of drugs we can do to manipulate this. Diet and training modalities might give you the ability to skew it 5-10%, if that.

What this means is that for any given weight you gain, x amount will go to muscle and y will go to fat tissue. If you gain muscle in a ratio of 2:1 with fat, then for every 2 lbs you gain, you'll gain 1 lb of fat. This works in reverse as well.

Now, don't freak just yet. There's a bit more to the regulatory system here, and what I just wrote doesn't imply what you think it might.