But does the study on which these headlines are based support such claims?
In a controlled experiment, there are independent variables (e.g. specific foods or nutrients) and dependent variables (e.g. health outcomes).
Ideally, an adjustment is made to only one independent variable, then the dependent variables are monitored for any effects of that adjustment.
If more than one independent variable is adjusted at once, it can’t be determined which adjustment is responsible for any observed effects.
The study in question compared an intervention group – instructed to follow a diet of vegetables, grains, legumes, and fruits without animal products or added fats, supplement Vitamin B12, and attend weekly support meetings – to a control group – asked to not make any dietary change (4).
The intervention group lost weight, decreased liver and muscle fat levels, and improved markers of insulin resistance, compared to the control group.
So, the intervention group did benefit from their low-fat vegan diet.
However, the study wasn’t designed to show if that’s because the diet was low-fat and/or vegan, as the headlines might suggest.
With so many changes to the intervention group’s diet, we can’t tell whether or how each change played a role in the observed health outcomes.
Furthermore, previous studies have shown prioritizing food quality to promote eating less, weight loss, and improvements in multiple disease risk factors, regardless of relative amounts of dietary fat or animal products (5,6,7).
Thus, it’s likely the intervention group’s benefits were due to an overall improvement in dietary quality, as evident by increased fiber intake, decreased caloric intake, and reportedly high adherence.
If you’re looking to improve your health, consider first prioritizing high quality, minimally-processed, nutrient dense foods.
This will likely take you further than worrying about any specific food or nutrient.
Oh, and take any news headline with a hefty grain of salt 🙂
You’ve got this.