Last post today - I'm waaaay out of time -
OK, this is a weak study in a variety of ways... on top of that, it reinforces what I've been saying all along; short term, calorie restriction trumps exercise.
The study is weak because, first, it's not calorie-matched, because it's not isocaloric on protein. Their design used a calorie breakdown of "30% calories from fat, 15% from protein, and 55% from carbohydrate."
The people in the diet-only group consumed 25% less of everything. The people in the diet-plus-exercise group ate 12.5% less of everything. So the diet group reduced their protein by 25%, and the other group reduced their protein by only half as much. You would, therefore, expect the diet-only group to do worse on lean tissue loss, because they're consuming less protein.
For clarity, assume you start at 2000 calories, and reduce all your food intake by 25%:
This is not isocaloric on protein, because the diet is consuming 25% less protein. Here's the kind of 25% deficit diet comparison that is fairly common to see:
The are isocaloric on total calories, but they are not calorie-matched on protein. The Locarb is being given a boost in protein (by telling people to eat lots of fatty/meaty food), while the Lofat is having protein cut sharply (avoiding fats often means cutting protein-rich food). This can be expected to have an effect on lean tissue, especially in the short term.
This would be a study that's calorie-matched on protein, and just varies the "energy calories," and compares exercise:
Now that I'm clear on what I meant, back to the study in question... it also has the problem that it has such a statistically small sample (only about six people per group) that it's not capable of giving any conclusion. The authors said so, themselves:
I'm going to gloss over the fact that they just said there's no difference between diet-only and diet-plus-exercise - why did you bring up this study? It does not support your claim that diet+exercise is better. But anyway, there's stuff worth looking at in the study.
The groups they compared were dissimilar - there was definitely an imbalance here! Compare the CR men's group (Calorie Restriction, or diet-only) with the CR+EX (diet + exercise)
The six guys in the CR group started with 25% body fat, while the five guys in the CR+EX group had 36% body fat! That's a big difference, and you expect the fatter guys to shed fat more easily.
The six guys in the CR group started with 67 Kg of Fat-Free-Mass, and the five guys in the CR+EX group started with 49 kg of Fat-Free-Mass. You'd expect the guys with so much lean tissue to lose more lean tissue on a diet.
So the CR group is already handicapped, before you consider that their protein intake is going to be cut twice as much as the CR-EX group.
But here's the rub... what actually happened?
I've edited the image to fit all the detail in a small picture and highlighted the results at the three month mark, but this is straight out of the study - at three months, the CR group (diet only) had lost more fat than the CR+EX (diet plus exercise) group, despite both having an "identical" 25% calorie deficit.
This is what I initially proposed in this discussion - the science suggests it's more effective to start with just a calorie deficit, and that it's necessary to later add exercise. This study does not contradict what I presented, despite not being isocaloric on protein, and despite handicapping the results by putting leaner men in one group.
This study also shows another interesting thing, if you read closely... for the first three months, everyone was put on controlled diets: "participants were provided with all meals that were prepared by the metabolic kitchen at the center." That includes the Control group. They were all fed a "maintenance" diet.
Did you notice that the control group lost over a kilogram of fat (like, 2.5 pounds), on average? That's because, prior to the study, they were overeating! (Or they under-reported how much they were eating before the study.) Being forced to eat "maintenance" was actually a reduction in food and caused some weight loss. Again, we all suck at estimating how much we eat. Soylent is great, in this regard.
For the last three months of the study (until month 6), "participants self-selected a diet based on their individual calorie target." Now look what happened to the Control group when they weren't having their meals prepped for them... their fat loss stopped, and they regained a bit... And look what happened to the CR group - when their meals were no longer being prepared for them, their fat loss slowed substantially. Again, we all suck at estimating how much we eat. Soylent is great, in this regard.
For completeness' sake, here's their results in terms of Fat Free Mass
Please note that this is on a different scale that the Fat Mass chart - it only goes down to -4 kg, while the other chart goes down to -8 kg, because the Fat Mass changes were much larger. At the end of six months, both test groups had lost roughly 2 kg of Fat Free Mass (lean tissue), whether or not they exercised, and had lost about 6 kg of fat, whether or not they had exercised. The Control group, which stopped eating like crap because they were part of a study, actually lost a kg of fat and gained a kg of muscle, which is what you expect when people pay just a little attention to their diet.
I'm surprised; I'd have expected the CR group to lose a lot more lean tissue, since they started with so much more of it, and because they reduced their protein intake twice as much.
Holy crap, look at the time...