Turns out that the truth sometimes isn’t what’s obvious or comfortable to believe. Some thing can seem true while being false, in fact. For example, I’ve long favoured approaches to nutrition that focus on the positive. Instead, of telling ourselves to eat less junk, we should instead focus on making sure we eat enough fruits and vegetable. And it’s true that eating enough fruits and vegetables is good for you, no matter what.
But here’s the rub. Sometimes it’s offered as an approach to weight loss. Don’t count calories or ban carbs (or whatever) just focus on making sure you eat enough of the good stuff. And you’ll lose weight. The idea is displacement. The thought is that carrots will take the place of cookies, arugula will be your go-to instead of apples, and you’ll eat fresh veggies before your meal instead of bread. That sounds right, doesn’t it?
But no. Sounds right, in fact, false.
“Researchers at the University of Alabama at Birmingham have found that increasing fruit and vegetable intake does not lead to weight loss, despite decades-old popular belief.
A team of investigators performed a systematic review and meta-analysis of data of more than 1,200 subjects in seven randomized, controlled trials to explore the weight loss effects of increasing fruit and vegetable consumption.
“Across the board, all studies we reviewed showed a near-zero effect on weight loss,” says study leader Kathryn Kaiser, Ph.D.,”
The displacement theory seems to be false, at least when it comes to fruits and vegetables. Randomized controlled trials are pretty much the gold standard when it comes to evidence.
“In the overall context of a healthy diet, energy reduction is the way to help lose weight, so to reduce weight you have to reduce caloric intake,” Kaiser said. “People make the assumption that higher-fiber foods like fruits and vegetables will displace the less healthy foods, and that’s a mechanism to lose weight; but our findings from the best available evidence show that effect doesn’t seem to be present among people simply instructed to increase fruit and vegetable intake.”
Three further things of note:
First, displacement seemed more effective when it comes to high protein foods. Simply adding two eggs for breakfast did reduce subjects’ overall calorie intake.
Second, the Precision Nutrition version of this theory comes with an additional tool, the idea that you only ever eat to 80% full. I wonder if that would make a difference.
Third, it’s still super healthy and good for you to eat the recommended amounts of fruits and vegetables, even if doing so doesn’t lead to weight loss.