Rule Basics

Any exercise you do will increase your calorie deficit and speed up weight loss. It does not mean that if you exercise you get to eat 500 calories a meal more or that you get to sleep 4 hours a night. This is bonus time, not substitution time. Exercise should be aerobic or "cardio" and not so much focused on resistance or "weight lifting." Aerobic exercise burns far more calories than weight lifting. In fact a hour of moderate weight lifting for a 160 pound person only burns 220 calories, while the same hour on a stationary bicycle with moderate effort burns 500 calories. In addition, resistance training can generate dangerously high blood pressures. In fact "squats" can raise the blood pressure to over 400 mmHg for short time periods.

While it is true that muscle is the body's engine and burns more calories than fat, most obese people have large muscles. They need these muscles inorder to carry the extra weight. With slow weight loss and adequate protein intake it is possible to lose weight, without losing signifcant muscle mass, without any resistance exercising. The only time inadequate muscle mass is at all common is in the elderly, especially the inactive elderly. In general the elderly only need very small weights to improve muscle mass as well.

The timing of the aerobic exercise does not seem to be important however some people will have a hard time falling asleep if they exercise to late at night. While exercise, both aerobic and resistance, do not affect ghrelin or leptin at all, aerobic exercise does effect insulin resistance. This likely occurs because aerobic exercise increases the activity of hormone sensitive lipase. This results in less fat being stored in the muscle in therefore improved insulin sensitivity in the muscle cells. Therefore if you have insulin resistance (diabetes, metabolic syndrome, PCOS or even just an elevated HOMA-IR score) exercise can be especially beneficial.

Each 250 calories of extra exercise a day will increase the rate of weight loss by 1/2 pound a week. To see how many calories each exercise burns check out an excellent resource at NutriStrategy's web site.