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Why are vegetarian diets so effective in preventing and treating diabetes? Maybe it’s because of the weight loss. Those eating more plant-based tend to be significantly slimmer, and not just based on looking at a cross-section of the population, but you can do interventional trials and put it to the test: A randomized, controlled community-based trial of a whole food plant-based diet.
The key difference between plant-based nutrition “and other approaches to weight loss [is] that participants were informed to eat the whole food plant-based diet ad libitum,” meaning eat as much as you want, no calorie-counting, no portion control, just eat. It’s about improving the quality of the food rather than restricting the quantity of food. And then, in this study, they had people just focus on diet rather than increasing exercise, just because they wanted to isolate out the effects of eating healthier.
So, what happened? No restrictions on portions, eat all the healthy foods you want. Here’s where they started out: on average, obese at nearly 210 pounds; the average height was about 5’5”. Three months in, they were down about 18 pounds; 6 months in, more like 26 pounds down. But you know how these weight loss trials go. This wasn’t an institutional study where they locked people up and fed them; no meals were provided. They just informed people about the benefits of plant-based eating, and encouraged them to do it in their own lives, their own families, their own homes and communities. And so, yeah, typically what you see in these so-called “free-living” studies is weight loss at six months, but then by a year, the weight creeps back or even worse. But in this study, they were able to maintain that weight loss all year.
And of course, their cholesterol got better too, but their claim to fame is that they “achieved greater weight loss at 6 and 12 months than any other trial that does not limit [calorie] intake or mandate regular exercise.” That’s worth repeating. A whole food plant-based diet achieved the greatest weight loss ever recorded at 6 and 12 months compared to any other such intervention published in the medical literature. Now, obviously, with very low-calorie starvation diets you can drop people down to any weight. However, these medically supervised liquid diets are obviously just short-term fixes, associated with high costs, high attrition rates, and a high probability of regaining most of the weight, whereas the whole point of whole food plant-based nutrition is to maximize long-term health and longevity. Even if, for example, low-carb diets were as effective, the point of weight loss is not to fit into a skinnier casket. “Studies on the effects of low-carbohydrate diets have shown higher rates of all-cause mortality”—meaning a shorter lifespan—”decreased [artery function], worsening of coronary artery disease, and increased rates of constipation, headaches, bad breath, muscle cramps, general weakness and rash.” And yet, still not as effective as the diet that actually has all the good side effects, like decreasing risk of diabetes beyond just the weight loss.
Yes, “the lower risk of type 2 diabetes among vegetarians may be explained in part by improved weight status. However, the lower risk also may be explained by higher amounts of ingested dietary fiber and plant protein, the absence of meat- and egg-derived protein and heme iron, and lower intake of saturated fat. Most studies report the lowest risk of type 2 diabetes among those who adhere to [strictly plant-based] diets.” This may be explained by the fact that vegans, in contrast to vegetarians, do not eat eggs, which appear to be linked to higher diabetes risk.
Maybe it’s eating lower on the food chain; so, you avoid the highest levels of persistent organic pollutants like dioxins, PCBs, DDT in animal products, which have been implicated as a diabetes risk factor. Maybe it has to do with the gut microbiome. With all that fiber, it’s no surprise there would be less disease-causing bugs and more protective gut flora, which can lead to less inflammation throughout the body that may be the key feature linking the heathier gut with beneficial health effects—including the metabolic dysfunction you can see in type 2 diabetes. And it’s that multiplicity of benefits that can help with compliance and family buy-in. “Whereas a household that includes people who do not have diabetes may be unlikely to enthusiastically follow a quote-unquote ‘diabetic diet,’ a [healthy diet] is not disease-specific” and can improve other chronic conditions, too. So, while the diabetic patient will likely see improvement in their blood sugar control, a spouse suffering from constipation or high blood pressure may also see improvements, as may overweight children if you make healthy eating a family affair.
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