The relationship between weight loss, health and exercise has changed over the last few years. As an exercise physiologist, I have modified how I advise people to exercise to lose weight. For two years I was an exercise consultant for Optifast, a hospital-based diet that is medically supervised and stressed the importance of lifestyle modification. I consider altering one's lifestyle following a diet to prevent subsequent weight gain the key to success for any diet and supported Optifast. My main mechanism of exercise assisted weight loss was cardiovascular training, preferably at a low intensity in the training heart rate range (60 to 65 percent of maximal heart rate). I felt if my client did this five to six days each week for 45 to 60 minutes, they had an optimal program for achieving weight loss gain as well as considerable health benefits.
However, current research and the prevailing literature has shown this exercise prescription to fall short of the mark as far as being optimal. Cardiovascular exercise is an still important part of exercise weight loss. We just need to alter the parameters a bit and add a new type of exercise:
RESISTANCE TRAINING. These are exercises such as lifting weights, calisthenics, resistance machines or any device that causes you to work your musculature so that you feel a burning in the muscle you are training. Training such as this allows you to build more muscle and tone the muscles you have so at least they are maintained. Maintaining muscle mass is important since one of the natural consequences of rapid weight loss is a reduction of muscle mass. So how do we know that increasing, or at least maintaining muscle mass, is so important to an optimal exercise weight loss program? Let me answer this question by reviewing a study recently published in an exercise physiology journal. Weight loss was monitored over eight weeks for a group of exercisers who trained cardiovasularly (CV) for 30 minutes and for a group of exercisers who trained cardiovascularly for 15 minutes and with weights (W) for 15 minutes. The CV group lost 1/2 pound of muscle and 3 pounds of fat while the CV/W group gained 2 pounds of muscle and lost 10 pounds of fat. For those of you not good at math that's 3 1/2 pounds of weight loss for the CV group compared to 8 pounds of weight loss for the CV/W group or a 225% difference.
How can resistance training lead to increased weight loss if cardiovascular exercise burns fat and weight lifting burns carbohydrates primarily located in muscle tissue? The fat that is burned during cardiovascular exercise is rather inconsequential to the amount of fat needed to burn that induces weight loss. It seems that exercise's contribution to weight loss is possible mainly due to increasing the body's metabolic rate. By increasing this rate one burns more calories (mostly from fat stores) throughout the day than one normally would. This metabolic rate is increased by two methods:
1) Increased hormones levels which drive the rate up and are increased by cardiovascular training and
2) Increased muscle mass that is expensive to maintain (30 to 50 cals/day compared to fat which is 2 cals/day).
So after all this information, what is an optimal exercise program to assist weight loss? I still advocate cardiovascular training since only this type of training is needed for optimal health benefit. I now suggest 15 to 30 minutes of resistance training 2 to 3 days a week. Intensity is variable and should be personalized to your needs. In general, high resistance (heavy weights) with few reps leads to gains in muscle mass while light resistance with many reps leads to more tone and definition.
These are general guidelines and some experience and/or counseling in resistance training is advocated to set up an optimal program for your situation. This program will change based on your age, fitness level and body molding desires.
If your weight loss program is not working and you are looking for an extra edge, I suggest adding the element of resistance training to your exercise routine. If you are considering an exercise based weight loss program I recommend the program outlined in this article for optimal results!