Most Effective for Weight Loss: Strength, Aerobic or Combined?

The prestigious journal of applied physiology published a study this month that has received much attention. The researchers compared the effect of strength training, aerobics and a combination of the two on an overweight population. It should be noted that this is the largest and, in the eyes, highest quality study published on the subject to date.

The results of the study surprised many experts. They are contrary to the recent mindset that strength training is better than aerobic training for weight loss. It is assumed that strength training will increase metabolic rate and thus “burn” more calories at rest. In addition, we are increasingly being criticised for prolonged aerobic exercise on the grounds that it is tiring, dangerous to the joints, and even ineffective for weight loss. The study results, as mentioned, found the opposite.

So my original plan was to write a blog about not being black and white in the fitness world, and as evidence I planned to quote the study above. But the original plan changed after reading the study in full.

What was the study about?

First, I will briefly present the structure of the study. 119 overweight participants (BMI 30) were randomly assigned to one of three training groups: strength, aerobic and combined. Without going into detail, the researchers did an excellent job in all aspects: precise tracking of the number of repetitions, weights lifted, target pulse rate, etc.

They also made sure to compare the strength and endurance of the participants with the weight of the body. They also made sure to compare volume, intensity and relative frequency between the three groups throughout the process. Another benefit, and perhaps the most important, is that the program lasted (hang on) 8 months!

How was study performed

At the beginning and end of the experiment, participants were weighed, measured for body fat percentage, lean body mass, aerobic fitness and strength tests. No significant differences were found between participants in the different groups at the start of the experiment, and although they monitored calorie intake throughout the subjects were asked not to alter their composition.


Statistically significant differences were found. A significant decrease in weight and waist circumference of the participants in the aerobic and combined group was measured, but not in the strength group. On the other hand, an increase in own body mass (muscle) was measured in the participants of the strength and combined groups, but not in the aerobic group.

Only the combined group benefited from both weight loss and an increase in own body mass, but they also spent more time training than the other two. So far, it’s all good and well, and fits with the original reason for writing the blog, but something has gone wrong. Why are we only shown statistical significance and not effect size? The answer came when I looked at the figures themselves. I have added for you the graphs from the study that you can do the same.

fat loss graph

For example, on the left side of the top graph we see the overall weight change. The left most turn represents the strength group, the middle one the aerobic and the right one the combined. A change of 2-3 kilos may have statistical significance, but has almost no practical significance. Especially when it comes to 8 months of training and an overweight population. The graph on the bottom left represents the decrease in fat percentage. Again, note the negligible changes ranging from 0.5% to 2%. The idea is repeated in each of the different metrics: waist circumference, lean mass, change in fat percentage and thigh muscle mass. The bottom line is that there was no serious change in any of the groups.

So what is the conclusion?

There are 3 to be honest.

  1. Although I couldn’t reinforce the original point I wrote the blog for, it is still true. There is no right/wrong in fitness. There is a lot of grey, and what works for one will not necessarily work for the other. Aerobic training is great for the body and mind and has benefits that are not present in strength training. Of course, the reverse is also true and for this reason it is advisable to combine the two.
  2. One should be very careful when drawing conclusions from studies. Statistical significance does not always equate to practical significance. Even without specializing in statistics, an in-depth reading of the averages, standard deviations, and looking at the various graphs can help miraculously in understanding the results.
  3. The most important conclusion from the study is the following: aerobics and strength can argue until tomorrow who is more effective for weight loss, but the results teach us very clearly that the most important variable is nutrition in general! Therefore, if you want to lose weight…. Eat less.

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