Always favor weight training with a fairly large volume if your goal is fat loss. As the regular readership knows, the Poliquin German Body Composition (GBC) program is designed to help you lose fat because it uses short rest intervals, relatively heavy weights, and all the large muscle groups to help you produce a lot of lactic acid and growth hormone. Naturally, GBC includes periodic changes to the program to help you continue experiencing adaptations and fat loss—changes in loads, tempo, rest periods, and set/rep schemes.
The critical point is that GBC or a similar training program is all you need for fat loss assuming your diet is in order. However, if you still like to do conditioning, either to be able to play sports, go hiking in the mountains, or run after your kids, etc., it’s important you know that more does not necessarily equal better for weight loss. Check it out:
Danish researchers had healthy, overweight young men engage in an aerobic exercise program for 13 weeks, 6 days a week. There was a control group, a 30-minute exercise group, and a 60-minute exercise group. Three out of the 6 exercise sessions had to be performed at 70 percent of maximal oxygen uptake and the other 3 were at a self-selected intensity.
Results of the study showed that both the 30-minute group lost 4 kg of body fat and gained about 0.4 kg of lean tissue for a total body weight loss of 3.6 kg. The 60-minute group lost 3.8 kg of body fat and gained about 1.1 kg of lean tissue for a total body weight loss of 2.7 kg. That’s right, doing double the amount of aerobic exercise, which equaled an estimated caloric expenditure of 600 calories a day resulted in almost exactly the same body fat loss as the 30-minute group that only burned an extra 300 calories a day!
Dietary records and macronutrient intake didn’t differ between the groups, so that is not the answer. Researchers note that aerobic exercise is “a poor weight management” strategy because the physiological changes that occur in the body lead to an increase in metabolic efficiency so that the body doesn’t burn as much energy for the same exercise volume over time, and it typically leads to lean tissue loss producing a lower resting energy expenditure.
They acknowledge that those reasons don’t explain what happened in this study since the 30-minute group produced an 80 percent greater weight loss than expected from energy calculations and the 60-minute group had a 20 percent lower weight loss than expected. They suggest that with aerobic exercise there may be threshold at which further increase of exercise doesn’t lead to additional weight loss.
Previous studies have produced better, more reliable fat loss results from high-intensity training using interval models and concurrent weight training with aerobic exercise. Unfortunately, there is a lack of well designed studies comparing weight training with aerobic exercise or weight training with interval exercise for fat loss. Most studies comparing weight training and aerobics strictly use weight machines, with faulty set/rep/load schemes, and too many isolation exercises, making them irrelevant to a real-life weight training program for fat loss like the GBC program.
Take away a few points:
You must match your training to your goal. If fat loss is the goal, you need to do weight training with a fairly large volume, compound movements, and short rest. Add intervals for conditioning. Never to steady-state aerobics for more than 30 minutes.
If muscle or strength development are your goal, program weight lifting accordingly and completely avoid aerobic exercise because it will impair strength and muscle development.
When it comes to creating an energy deficit for fat loss from exercise, a calorie is not necessarily a calorie. The same goes for diet—eating too much energy can make you fat, but not all calories are created equally. To read more on this topic, check out Why the Calorie Approach to Weight Loss Doesn’t Work.
Rosenkilde, M., et al. Body fat Loss and Compensatory Mechanisms in Response to Different Doses of Aerobic Exercise. American Journal of Physiology. 2012. 303(6), R571-577.