Aerobic Exercise Alone Is Not A Reliable Weight Loss Tool
We all know that long term weight loss is facilitate by creating a calorie deficit.
In this respect, “eat less, move more” is correct, albeit somewhat simplistic in description.
One of the many reasons it can be perceived as simplistic is that “calories in vs calories out” are often seen as two completely independent variables. Do you want to lose weight? Ok, then you can either eat less, move more or both.
Eat less? Reducing calorie intake through food.
Move more? Commonly this looks like cranking up the exercise volume.
How many people do you know who want to lose weight so they immediately start doing hours of aerobic training in hope of rapid results?
Unfortunately, aerobic exercise in isolation often doesn’t yield the weight loss results many people anticipate.
Why is this? If it is about calories in vs calories out, increasing the amount of calories you burn should reliably act as a catalyst for weight loss.
Well, this is where compensatory behaviours come in. Increasing the volume of aerobic exercise (and therefore increasing the ‘calories out’ portion of the equation) frequently has a knock-on effect elsewhere.
To examine this phenomenon, a research trial had participants complete two different doses of aerobic exercise for 24 weeks. The lower dose reflected recommendations for general health and the higher dose reflected recommendations for weight loss and weight maintenance. These results
were compared to a control group and were examined for energy intake, activity and resting metabolic rate.
What did they find?
In the lower dosed exercise group, 57.6% of participants lost weight.
In the higher dosed exercise group, 76.5% of participants lost weight.
When looking at the actual rate of weight loss and comparing it to the predicted weight of weight loss for the number of calories burned, 76.3% and 90.2% of participants compensated in reaction to the exercise intervention in the lower and higher doses of exercise groups, respectively.
This image shows how weight change differed from predicted weight loss. Individual subject data is plotted within the blue superimposed lines.
Why was this?
Physical activity and resting metabolic rate measurements were not significantly altered in any of the groups (excluding the structured exercise).
However, the participants who compensated the most reported higher appetite ratings and increased energy intake.
To conclude, although aerobic training can promote weight loss there is a highly individual response to isolated exercise interventions and some people may notice increases in appetite whereas others do not.
If you want to lose weight, it would make sense to pay attention to changes in appetite and regulate your food intake rather than relying solely on exercise as some people may not have great success with this alone.
- Effect of different doses of supervised exercise on food intake, metabolism, and non-exercise physical activity: The E-MECHANIC randomized controlled trial