Will Giving Up Meat Make You Lose Weight?
In a headline better suited for a late night infomercial, this week the Washington Post published an article, “How Americans Can Lose a Lot of Weight Without Giving Up a Single Calorie.” While certainly eye-catching, like many reports on scientific research, the article gives a misleading impression of provisional research findings.
The article asserts diets higher in plant-based foods can lower weight without reducing calorie intake:
According to the study, conducted by agricultural economists at the University of Nebraska-Lincoln, Americans could cut 2.57 points off their average Body Mass Index score by adopting a Greek (Mediterranean) diet; 2.13 points by eating like Finns (the Nordic diet); 1.96 by adopting a French diet and 1.48 by eating like the Japanese.
But before you toss out the meat from your refrigerator, what the study actually found was simply a correlation between plant-based diets and lower BMI (the crude, but often used measurement of obesity). Keep in mind that divorce rates in Maine correlate nearly perfectly with per capita consumption of margarine.
In fact, the research cited has still yet to go through essential steps that maintain academic accountability—namely being peer reviewed and published in an academic journal.
Here are some things the review board should consider:
- The study does not account for any true measure of physical activity, a factor Harvard public health experts consider to be half of the equation when it comes to weight. And considering that the United States was the heaviest country, it’s not surprising that all other countries, except Japan, have lower rates of inactivity than the U.S.
- All reputable research must compare apples with apples. For comparing international diet, the study summarized in the Washington Post used data from the Food and Agriculture Organization of the United Nations, which the researchers themselves say “likely overestimates actual caloric intake.” This is particularly problematic because we can’t know whether this is overestimated in all countries the same. If it is not, these findings are undependable.
- Assuming the findings have some validity, the study still assumes that diet composition exists in a vacuum. In reality, diet evolves slowly out of everything from cultural norms and practices to the surrounding geography and what’s available. To assume that consumer demand and food supply can easily change is not grounded in a practical understanding of the real world.
So, just as you would be skeptical of diet plans advertised with too good to be true claims, news reports with similar claims should also furrow your brow. The reality is that diet is complicated, and anyone that uses one study to make simple conclusions shouldn’t be taken at face value.