(Nov 28, 2023)
1/3 of Americans are dieting at any time, and typical dieters try again 4 times/year! 80% start on their own, but some try groups or organizations like Weight Watchers, with special foods or menus, or healthful choices at restaurants, shopping and cooking. The US government publishes revised Dietary Guidelines for Americans every 5 years (they can’t make up their minds either!). The current 2020-2025 guideline has been criticized by whistleblowers for ignoring newer scientific evidence and for restricting communication between its members. It also recommends much lower sodium intake than 95% of the world population, without evidence of health benefits except in certain specified diseases.
Why such confusion? Many weight-loss trials are limited by small samples, limited generalizability (“the devil is in the details”), lack of blinded determination of outcome, lack of diet-adherence data, and large loss to follow-up. A hidden factor in government studies is lobbyists from fast food chains, food factory companies, manufacturers of additives, preservatives, pesticides & herbicides, & corporate agriculture (most family farmers are gone).
Many popularized diets have come and gone, like the Zone diet & South Beach diet, with variable proportions of the major food groups — carbs, protein, & fats. They tend to agree on the importance of eating healthful-sourced foods, including organic & free-range or wild-caught.
What about vegan diets? They avoid all use of animal products (not just diet, as in vegetarianism), including animal-tested products, and are concerned about animal welfare & environmental costs. They are lower-cost, more environmentally friendly, and potentially less chemically-toxic. Among their problems are vitamin B12-deficiency & vegan protein’s tendency to be more inflammatory on the immune system. Common plant-food sensitivities include GLUTEN (wheat, rye, barley), corn, soy & other legumes (bean family), & nightshades (tomatoes, potatoes). (Paleolithic people didn’t eat grass seeds or beans, so our biology is not well-adapted to these foods; they can trigger auto-immune diseases and other chronic health problems that are seldom suspected as food-related.)
Ketogenic (low-carb high-fat) diets promote weight loss by suppressing appetite (Obes Rev. 2015 Jan;16(1):64-76). This may help explain the increasing rate of obesity that has more than tripled since the early 1960s, when the “Low-Fat Diet” recommendation was introduced.
The different weight-response to dietary fat content seems to relate to the insulin hormone, which stores excess glucose (from digested carbs) in the form of body weight for “the next famine”. Without enough insulin, the blood sugar would go too high, which damages body tissues, but having enough insulin to control the blood sugar by storing it promotes weight gain (as diabetics know). However, the body can’t store excess dietary fat (because there is no insulin-equivalent for it), so the appetite shuts off instead. This seems to be why high-fat diets lead to more weight loss than low-fat diets (Lancet Diabetes Endocrinol. 2015 Dec;3(12):968-79). (Weight-loss also reduces coronary risk & diabetes.)