Low/no carb diets have become incredibly popular..In fact, the vast majority of weight loss/get fit diets incorporate some form of extreme carbohydrate restriction. And this is for good reason, it works. Carbohydrates are by far the most usable and easily burned energy source between the three (carbs, fats, proteins). So by restricting them, we limit our bodies quick access to an energy source, thus in order to function, it forces our body to turn to fat, body fat and convert protein for energy. While this sounds like it may be uncomfortable to have no energy source, our bodies are actually quite good at it.
After restricting carbs over a period of time , we get ever more efficient at mobilizing fat to use as energy to substitute for our lack of available carbs. This is why low carb diets are so effective as they make your body BETTER at burning fat.
There is however, a downside of low/no carb diets. This downside has to do with our energy needs an expenditure. While our body is able to convert fats and proteins for energy, it is not an incredibly fast process. When we are sitting around doing nothing or sleeping, our energy expenditure is very low, and at these times we can fuel ourselves adequately even if we are carb depleted by drawing from fats. However, when we are active, be it either exercising, playing sports or just doing chores, our energy usage is significantly higher, and the rate at which we are burning energy exceeds our ability to produce it from dietary fat/body fat and proteins. This leaves us feeling tired and slow and negatively impacts our performance. You may have noticed this if you have ever gone into weight train when you are low carb or maybe just haven’t eaten much that day. You will be much weaker and feel tired sooner.
So low/no carb diets are great for weight loss, but are horrible for performance, and we need to have great workouts to achieve our goals. We can remedy this by focusing carbohydrate intake only when we need it, like in the time leading up to a training session. This will serve three purposes. 1) It will provide you with quick acting fuel so you can perform much better in the gym, thus burning more and lifting more, resulting in better muscle response. And 2) you will actually burn MORE overall calories by adding in carbs pre-workout, so in the right amount, it is a wash as far as energy in vs energy out. Ideally, the workout will burn through all of the carbs you ate, so by the end of the workout, you will be right back to using fats for energy, except now you had a better workout and more muscle growth/toning/fitness. Not only that 3) the eating of more carbs will in effect exercise your metabolism too, so you may actually burn more calories the rest of the day even in downtime, not to mention feel better/less lethargic.
So how much carbs should you eat? This is something you’ll want to play with. It is dependent, of course, on your metabolism as well as how demanding the activity/workout. For normal purposes, somewhere between 50-150g of carbs should be ideal for normal workouts, and no big deal if by the end of the workout you are back in a carb depleted state, you still got the benefit and a better workout.