“Dieting” for Weight Loss


Childhood Obesity News mentioned a meta-study on the long-term effects of dieting. The trio of researchers, from UCLA and the University of Minnesota, wrote that their intention was to “evaluate whether weight loss improves health.”

Just a moment, please! With rare exceptions like anorexia, isn’t it pretty much universally accepted, that weight loss improves health?

Academic productions like this might be where the Fat Acceptance movement found some of its ideology. One paragraph of the article, first published by Social & Personality Psychology Compass, reads:

The objective of this review is to assess the long-term health outcomes of weight-loss diets…

Our review of randomized controlled trials of the effects of dieting on health finds very little evidence of success in achieving this goal.

If diets do not lead to longterm weight loss or long-term health benefits, it is difficult to justify encouraging individuals to endure them.

Believing that the ultimate goal should be not weight loss, but health improvement, these authors address the possibility that the reducing diet accomplishes neither weight loss nor anything else except frustration and feelings of inadequacy and failure.

As is the custom, the researchers pored over a large number of publications to choose the 21 studies that fulfilled their criteria. They specified five particular lab-measurable health outcomes to track: cholesterol, triglycerides, systolic and diastolic blood pressure, and fasting blood glucose.

Did weight loss lead to those looked-for improvements? Not really. The improvements were minimal, and not correlated with weight change. Weight loss did correlate with less diabetes and fewer strokes, and allowed some patients with diabetes or hypertension to cut down on their medications.

Motion to the rescue

The researchers found that exercise itself seems to be responsible for many health benefits — just the exercise, not the consequent loss of weight due to exercise. In other words, it “leads to health benefits in the absence of weight change.” While the reducing diet does not seem to count for much — nor the shedding of pounds — what makes the difference, apparently, is activity alone. Interestingly, and although this was not tested, they suspect that such factors as social support and engagement with the health care system may count for more than calorie reduction.

Only people who do research can comprehend the mountain of detail involved in such chores as, for instance, determining that dozens or scores of studies have enough essential commonalities to justify matching them against each other, or combining the evidence they contain. Imagine how difficult it must be to compare studies with non-conforming timeframes.

And yet, for some reason, the various practitioners of science don’t always make things easy for each other. The paper includes an intriguing paragraph, worth lengthy consideration, about what the authors call an “odd convention” of their field:

The most widely accepted standard for a “successful diet” is that set by the Institute of Medicine (1995), which states that an individual must maintain weight loss for a year. Although our focus is on long-term health outcomes rather than on weight loss, we use the same timeframe of assessing outcomes at least one year post-diet. The Institute of Medicine, however, counts the one year as beginning when the diet begins, rather than when the target weight is reached.

Social science researchers have discovered that life situations can improve just because a person has signed up for a program, and not even done anything yet. Often, finding kinship in a support group or receiving attention from a counselor can help a person heal through the beneficent effects of connection. Even though it does not involve pills or other physical intervention, this phenomenon is a type of placebo effect, which we will talk about next time.

Your responses and feedback are welcome!

Source: “Long-term Effects of Dieting: Is Weight Loss Related to Health?,” DishLab.org, 2013
Photo credit: Flavio~ via Visualhunt/CC BY

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