Many people think that weight training will increase muscle mass. This is possible, if you are using the right approach. Further, they think more muscle mass will increase resting metabolic rate and that will cause our bodies to burn more calories over the course of a day, ultimately leading to weight loss. Unfortunately, it’s not that simple.
So, let’s ask the question: Does strength training increase resting metabolic rate and ultimately help with weight loss? Before we answer the question, let’s set some things straight. First, remember that resting metabolic rate generally ranges from 1,200-2,000 kcal/day (most people fall in between 1,200-1,500 kcal/day) and is not significantly different between people of different aerobic fitness levels. Resting metabolic rate is also independent of training status. Heavier people have a larger mass to support and have a slightly higher resting metabolic rate. Each pound of muscle mass burns about 6-7 kcal/day.
Burning more calories helps in weight reduction only if our caloric expenditure is greater than our caloric consumption, as I stated in my Why People Get Fat piece. What many people don’t realize is that when weight is lost, resting metabolic rate decreases, even if muscle mass is maintained with strength training -OR, at best- it stays the same when exercise (rather than diet alone) is the reason for weight loss.
Most research shows that while our metabolic rate may be elevated right after an exercise session because of an increase in oxygen consumption, increased metabolic rate is not a chronic adaptation of strength training. The smaller body of research that does show an increase in resting metabolic rate following chronic strength training, shows a magnitude of change that is relatively small compared to what is needed for weight loss. However, when weight loss is achieved by exercise instead of by diet restrictions, what strength training may help prevent is a DECLINE in resting metabolic rate. An exception to this would be older adults. They are more likely to show increases in resting metabolic rate due to age associated losses in muscle mass.
So, does strength training increase resting metabolic rate and ultimately cause weight loss? Most of the research is saying no or not enough to notice a significant difference calories burned at rest. What it is more likely doing is helping to maintain lean mass and help prevent a decline in resting metabolic rate.
Feel free to contact me if you want information about the literature I have reviewed.