For the longest time, the dietary advice was simple, and more than a little judgemental. If you’re big, it’s because of your diet, so eat less fat. Except we’ve learned it’s not that simple: Low-fat diets can, ironically, expand your waistline, and we’ve learned our own bodies fight fat loss, and the sugar we’ve replaced the fat with might be killing us, oh, and it might also be making you bigger.
Now a new scientific study is here to muddy the waters even further by saying that, no, long-term, eating fat is what makes you fat.
The study, run by a Chinese research team, is fairly simple in design. They take three sets of genetically similar mice, and feed them three diets: One high in protein, one high in fat, and one high in sugar, step up the percentages over time, and see which mice get bigger. The mice being fed protein and sugar in higher percentages didn’t grow in size, and the ones being fed a high-fat diet did. This seems to be because the fat lit up reward pathways in the brain, so as the mice ate more fat, the happier they felt. This held across multiple genetic types of mice. And there’s not good news for the high-protein crowd, either, as the mice didn’t lose weight on that diet either.
That said, there are a few points worth considering before chucking your butter in the trash. The first is that dietary fat is a macronutrient that you need in your diet — we’re just getting too much of a good thing. Secondly, this study looked only at weight gain as a function of food consumption, not the overall health of the mice. Your body size is just one of many, many health indicators you need to consider. It also didn’t look at weight loss; none of these mice were put on the wheel to lose weight, and because they were all basically the same, genetically, there weren’t a diversity of mice sizes to test weight gain on. Finally, the weight gain depended heavily on the percentage of fat, which was as high at 80% in the experiment, and doctors think 20 to 30% is fine for our daily eating.
And that’s not even considering the increasing evidence that our genetics have a powerful influence on our dietary needs. In short, this study is a good reminder that, at least to some degree, that we shouldn’t get so wrapped up in the details that we forget the larger picture. But we should also remember that we’re not a strain of carefully bred, genetically engineered mice, either, and that our understanding of what we eat, why we eat it, and what it can do for us is still in its infant stages.
(via Science Direct)