Fly hearts are unrelated to mammal hearts. Flies belong to a completely different phylum. Pretty much everything about the organs of flies is different to humans. They don't have lungs, they don't have a brain, but a cerebral ganglion, they don't have a full stomach, but a stomodaeum, etc. More importantly, they don't have oxygen rich blood or red blood cells. I realise that flies are often used for genetic studies that have implications for humans, but I very much doubt this study says anything much about human heart health.
There are things we can do with flies that we simply cannot do with humans. Doing the research in flies is often a way for us to get an idea of how things may work in humans and others. Also, while we are physiologically different, we have quite a bit in common at the cellular level.
The trade-off of relevance to humans, and short generations (a day) seems to be best with fruit flies. I'm sure scientists have worked out what areas of research have worthwhile comparisons with mammals.
I think that 'many small meals' is specific to calorie restricted diets, in order to avoid feeling so hungry. A time restricted diet is a different approach; although it could be combined with calorie restriction, this is not a requirement.
Human trials should give us a better idea of how effective a time restricted diet will actually be. Personally, I think that time restriction is more realistic than calorie restriction for the majority of people, so that's why I'm excited about this research.
For weight loss/management, it's recommended to eat your daily calories over 6 meals throughout the day. But, the general idea isn't to keep you from feeling hungry, but rather to keep your blood sugar relatively constant, so the body doesn't enter "hoard energy" mode (where muscle is preferred as an energy source over fat) and you aren't spiking your bloodstream with huge surges of glucose (and thus insulin, which is what prompts the storage of glucose as fat) after binging.
I hear it repeatedly on fitness forums, but haven't seen it tested. I do leangains myself, which is intermittent fasting + barbells. In the leangains community the idea is widely derided. Martin Berkhan, the man who made leangains, is pretty scrupulous with citing studies, so if something supported the six small meals idea I suspect he would have mentioned it.
I did a few google scholar searches, but I'm not familiar with any specialized terms that might be relevant. Are there studies I might be missing?
I don't know, actually. I've heard the idea repeated so regularly in diet and exercise literature that I'm not sure I've ever looked for studies on it.
[1] is the closest thing I can find on the subject, which showed that high-frequency diets substantially reduced insulin levels in the blood. This seems to be the Ur-study from which the idea was spawned.
On the other hand, you have [2] which shows that even though glucose levels fluctuated more on 3-meal plans, resting metabolism and satiation were both higher, though there was no significant effect on fat oxidation.
[3] suggests that regular meals (as opposed to irregular meals) "have beneficial effects on fasting lipid and postprandial insulin profiles and thermogenesis."
Finally, [4] seems to sum up existing findings as "some for, some against, most neutral, tl;dr eat fewer calories".
I wish more studies and nutritionists would focus on satiation. "Eat fewer calories" isn't practical, in a lot of cases, since it involves actively fighting hunger. Ceteris parabis, the more satiating of two diets should lead to more weight loss.
The diet and exercise popular literature is a mess. A lot of it is either seventh hand knowledge repeated to the point of truth, or articles written for SEO purposes to capture readers wondering "will food X burn fat/increase gains"?
Completely ridiculous conclusions based the information provided. Even if the standard diet were quantity restricted, it does not indicated the amounts actually ingested by each fly group. Timing as the sole controlled factor for an actual scientific experiment, requires that each group ingests the same amount. As such, the amount should be no more than that which can be ingested in a 12 hour period. To relate the finding to circadian rhythm, the timing should be varied based on normal sleep patterns.
