The purpose of this study was to evaluate the effect of resistance training, diet, and resistance training + diet on bod composition changes (fat mass and lean body mass). This study was carried out using premenopausal women.
This study recruited 40 women ages ranging from 25-40 years old. These women were all premenopausal, had normal daily activity levels, yet were not intentionally exercising.
In essence, the researchers wanted middle aged women, whom were healthy, yet not really exercising on a regular basis. This is a great cohort to study, since it allows us to observe how either of these variables (resistance training and diet) affects body changes, for beginners. Further, it then allows us to view how a combination of the two differs from either alone.
This type of research is important because it provides a starting point for those looking to get in better shape, yet aren't sure the proper route to take.
From here, subjects were placed into one of four groups:
Note: Resting metabolic rate (RMR) is determined by gas exchange. You sit in a room or under a device which measures gas exchange through breathing and eventually determines the amount of calories you burn at rest for a given amount of time, which is then extrapolated for a daily amount.
For subjects included within the "diet" or "diet + RT" group, the researchers manipulated calorie intake on an individual basis.
Using formulas, (harris benedict), researchers determined estimated Resting Metabolic Rate (using things like height, weight activity, etc.). Afterwards, subjects then underwent actual RMR testing.
According to how closely the estimated matched the actual RMR testing, the researchers manipulated intake. For example, if the subjects RMR was within 10% of the estimated RMR, then this individual followed the actual RMR number.
If the RMR was 10% greater than the estimated, then the calorie intake for that individual was set at 10% LESS than the actual RMR. If actual was 10% less than predicted, calorie intake was set at 10% above actual.
Here's a more clear example:
It might seem a bit strange, but this technique is optimal since everyone's metabolic rate is unique. If measured RMR is close to Estimated, it's probably fairly accurate. This procedure is just done to try and better match the subject's ACTUAL RMR rather than just taking the testing and estimations as gospel. It's always better to have an average.
Note: this method was also used for individuals completing resistance training. The fact they exercised did not change the nutritional protocol.
When it comes to an exercise protocol for a study like this, the above is pretty much as good as it gets. The researchers used a full body routine, using typical bodybuilding style ranges of repetition and weight.
Theoretically, this range should provide a decent stimulus for increasing muscle mass, while also being fairly metabolically demanding. Further, this is a decent route since if they began incorporating things like HIIT or metabolic resistance training, they run the risk of skewing results (because weight loss may then be attributed to excess high intensity cardio).
Overall, there aren't many confounding factors when it comes to their exercise prescription in this study.
In the above, you can see that there is very little difference between groups. However, there was a significant decrease trend for diet only (β = -1.35; 95% CI = -2.03, -0.67; P = 0.0004) and diet + resistance training (β = - 1.68; 95% CI = -2.51, -0.85; P = 0.0006).
In the above figure, we see that all conditions were significant with regards to reducitons of body fat % (except control).
All three groups showed significant decreases in body fat mass. However, the researchers executed additional statistic for this test and concluded that diet + resistance training had a greater decrease in terms of time and extent, than resistance training alone. There was no significant difference in this rate when comparing to diet only.
In the above, the researchers determined that the only group to show a significant increase in lean mass was the resistance training only group (β = 0.76; 95% CI = 0.32, 1.2; P = 0.002).
Honestly, this makes sense. These participants focused solely on resistance training while also consuming a normal amount of calories. This is a perfect recipe for muscle growth, while any of the others (calorie deficits) were not optimal for this outcome.
What This Means
Based on the findings in this study, it's increasingly more safe to assume that including both a restriction of calories in addition to a resistance training protocol yields superior changes in body composition that if you were to only implement resistance training or simply diet, alone.
Really, this isn't groundbreaking at all. It makes sense that a combination of exercise and diet would yield superior results. However, it at least provides us a metric for how much of a difference we should expect.
It tells us that while either diet or exercise may work for changes, combining the two is certainly a better option if you want quicker and more drastic results.
Moving forward, I would assume that subjects would likely see even greater results if some form of cardio type training was intermittently added to the protocol. Albeit, it's unknown to what extent this would occur.
Future studies should include three - four additional groups
Surely that may prove difficult but it's certainly something worth considering, given that many people decide that jogging is the best way to get in shape. Surely the scientific community agrees that diet and resistance training is the superior route but many lay-persons don't necessarily follow that logic.
Why This Should Matter To You
It matters because it sheds light on the subject of dieting and resistance training plus the relationship they have with each other when it comes to weight loss. Arguments over importance of training and diet have been taking place for years. This research at least sheds light on the theory that a combination of diet and exercise is superior. Further, it strengthens the notion that there is not quick fix. If you want real results in a reasonable amount of time, you'll need to work for it.