Caffeine taken 45 minutes before exercise can facilitate a shifting to burn more fat and less glycogen. It increases the breakdown of fat, freeing fatty acids, which are used for producing energy during exercise. Conversion of fat to energy is about 30% more efficient when caffeine is consumed prior to exercise. The caffeine-enhanced fat breakdown can only occur during exercise. While the fat is being burned, glycogen and glucose are being reserved, allowing blood sugar levels to remain higher for longer. Higher glucose levels ward off hunger. The brain functions exclusively on glucose, and higher blood sugar levels facilitate thinking.
Caffeine Effects on Weight Loss & Performance
You may experience an enhancement in both performance (ease at which you complete a session) and the rate in which your body releases and uses fat during your cardio session by consuming a small to moderate amount of caffeine. You just need cycle the use of caffeine on and off, approximately every 4 weeks, otherwise your body will become accustomed to it, thus losing the benefits.
However, there are downsides definite downsides. Caffeine can increase urination by up to 30% (leaving you dehydrated), cause upset stomachs and even result in heart attacks. Expert advice is to that a coffee before going to the gym is fine to perk you up, but stay away from caffeine pills and supplements.