What is the right amount of carbohydrates to consume each day when trying to burn fat? 50g? 100g? 200g? The answer is it depends. Factors such as how lean the person is, how well they handle carbs, their current level of muscle development and training volume all effect the answer. Experimenting to find the right level for you is really the best course of action.

But more important than how much is when to consume carbohydrates.

If you consumed a huge bowl of pasta last thing at night before bed do you think that would have the same effect as having the same huge bowl right after a workout? The answer is of course no. Having a large amount of carbohydrates last thing at night will cause rapid increases in fat gain for most people. However that same dose of carbs straight after a workout is likely to increase muscle gain significantly (especially if coupled with a healthy dose of protein).

The reason is insulin sensisitivity. Insulin is the hormone which regulates blood sugar levels. It can be your most powerful weapon for building muscle, but can also cause you to gain fat faster than you can say "ugh where did my abs go!". When you eat protein or carbohydrates your body releases insulin so that the excess calories, which are not needed for immediate energy, are stored for later use. This means they are converted into glycogen to be stored in the liver and muscles. However, once these stores are full, the excess is turned into bodyfat. 

The problem is the more excess carbs you eat, especially fast absorbing carbs, the more insulin your body must release to stabilise your blood sugar. This is because your body's cells become increasingly insulin resistant. The cell's receptors get used to the level of insulin and need more in order to absorb the glycogen.

However the body's fat cells tend to be less insulin resistant. This means the more insulin resistant you become, the more you will gain fat rather than store excess calories as glycogen. Your muscles and liver will hardly take notice of the high insulin levels while your fat cells suck up all the excess calories as body fat.

This makes insulin sound pretty bad but it also has its benefits. Insulin is also extremely powerful at driving nutrients into the muscles. It will force amino acids and other anabolic nutrients right into the muscle cells causing faster recovery and dramatically increased muscle gains. Plus there are certain times when insulin sensitivity is so high that your muscle cells will suck up almost anything you eat.

After a prolonged period of fasting your body is primed to replenish its glycogen stores in the muscles and liver. This means first thing in morning your body will put carbs to far better use by replenishing muscle stores, dragging amino acids and other anabolic substances with it. So by having a breakfast with moderate carbs and high protein you will increase muscle growth. 

However there is also another extremely anabolic time to consume carbohydrates. The term peri-workout means the period just before, during and after a workout. This is the time when carbohydrates have the greatest effect on muscle gain. Research has shown that weight training significantly increases insulin sensitivity in the muscle cells. This causes a huge increase in partitioning of nutrients towards the muscles at the time when they really need it. Therefore, muscle and strength gains go up dramatically without any fat gain.

So the answer is if you want to gain muscle while remaining lean, or lose fat as fast as possible without losing muscle and strength, then time your carbs to the peri-workout period and first thing in the morning. By going low-carb the rest of the time you will burn fat and increase insulin sensitivity so that when you consume carbohydrates there will be an even greater anabolic effect.