The results of a new study suggest that counting calories might not be the best way to measure the effectiveness of exercise as a means to lose fat.
A study, conducted by Auckland University of Technology in New Zealand, shows that different workouts have different effects on the hormonal and physiological changes that take place in people’s bodies, even if they burn the same number of calories.
Published this month in the Journal of Science and Medicine in Sport, the study showed that certain types of exercise can trigger far greater fat-burning and other healthy responses in the body than simple calorie counting suggests.
The study looked to identify the causes of differences in body fat reductions, which an earlier study had identified, between resistance training and cardiovascular workouts.
For the research, the Auckland University team compared the levels of Human Growth Hormone (HGH) present in subjects after they had completed resistance training – in the form of Bodypump, a low-weight, high-repetition resistance training class created by Les Mills International – and cardio cycling workouts.
The results showed that those completing a resistance training session had HGH levels 56 per cent higher than those in the cardio test group.
Bryce Hastings, head of research for Les Mills International, said: “HGH oxidises fat and builds lean muscle tissue.
“That’s important for ongoing calorie expenditure because muscle burns more calories than fat. The more muscle you can build, the more calories your body will burn long-term. Combine that with increased fat loss and the result leads to rapid changes in body composition.”
Resistance training also resulted in higher blood lactate levels.
Those doing resistance training showed lactate levels up to 81 percent higher than those completing cycling sessions.
Lactate levels build when the muscles work hard, and it is the accumulation of lactate from exercise that sparks the growth hormone response.
The study strengthened the view that the beneficial effects of certain exercise types – such as resistance and high-intensity training – can last long into the recovery period after the actual workout is over.
According to Nigel Harris, the study’s lead author, the results also have implications for the exercisers relying on wearable devices to measure their calorie output during workouts or training sessions.
“Calories matter, but so do the effects of an exercise session on hormonal and physiological responses, which are known to have positive, long-term effects on body composition," Harris said.
“A wearable device which only measures heart rate and calorie count may therefore be too limited a tool to get an adequate understanding of the other, arguably more important, adaptations taking place in our bodies when we exercise.”
Hastings added that the study points to how much more people need to know about the effects of certain exercise types.
“It’s complex," he said, “and just counting calories misses a big part of the jigsaw. We now know that.”