by Alejandra "Alex" Ruani
The BBC announced that low-fat diets are better than cutting carbs for weight loss. But on that same day the Daily Mail wrote: low-carb is best for weight loss. The opposite! When I dug into these clashing news articles, I noticed they were talking about the same scientific study… Confused? Well, I was.
How is it possible that the journalists concluded the opposite by looking at the same study? Did they even bother to read the full paper? Probably not. But I did. And here’s what I found:
The low-carb diet (140g carbs + 108g fat a day) led to more weight loss (1.85kg vs 1.3kg), while the low-fat diet (352g carbs + 17g fat a day) led to more fat loss (463g vs. 245g). So the low-carbers lost more weight but less fat, while the low-fatters lost less weight but more fat! If you carry excess body fat, fat loss is better for your health than just “any” weight loss, e.g. muscle loss.
Just bear in mind that this was a small study with only 19 obese people, locked in a “diet lab”, fed every bite they ate, for 6 days! Not doable in real life, right? Besides, a 6-day outcome can’t predict the effects of following either diet in the long term, no matter how many fancy probability models the scientists run… Interesting study, though it doesn’t fully settle the low-carb/low-fat debate (sorry!).
Finally, the findings in such a small group of 19 obese people are unlikely to apply to everyone. Individual genetics and biochemistry have a huge impact; and some can tolerate low-carbing better than others. Here’s the full study in PDF format, published in the peer-reviewed journal Cell Metabolism (Hall et al., 2015). I recently talked about how journalists and health bloggers “spin” headlines; see this list of red flags so you too can spot fabricated information online!
Source: The Health Sciences Academy.