Small Change Theory? Don’t Count On It

It’s pretty easy to find advice to make small changes that stick if a person wants to lose weight – or keep from gaining weight. It certainly sounds authoritative when a PhD psychologist offers up small change theory as a winning strategy:

“When you focus on just a couple of small changes at a time, you begin to ingrain some healthy habits that last for a lifetime, rather than trying an all-or-nothing approach that more often than not fails because it’s too hard to follow.”

But does it work out to be a winner? Not so much – if the challenge at hand is overcoming or preventing the progression of obesity. At least that’s the finding of a careful RCT published recently in the Canadian Medical Association Journal.

A 36-Month Study

This was a 36-month study that randomized 320 persons to either a program of small changes in health behaviors or monitoring visits only, with no encouragement to make changes in lifestyle. This included people with a BMI between 25 and 40. The average was 32.6. The small changes were all about diet and exercise. People in this group were guided through self-assessments and goal setting consistent with the small changes theory. In both groups, people checked in quarterly for 18 months and then every six months for measurements of weight and waist circumference.

In the end, the small changes made no difference in the primary outcome – body weight maintenance. Researchers did note, in a post hoc analysis, that people with a BMI less than obesity might have seen a benefit. It seems reasonable that small changes might make more of a difference for people who have overweight but not obesity. Of course, that’s not what this study was designed to show.

Overall, people in the small changes group had a significant benefit in the first 15 months. But it faded out within 24 months.

Prior Research

The authors of this new study note that their research has an outcome that’s different from earlier research:

“Our principal finding counters that of a previous report, the Study of Novel Approaches to Weight Gain Prevention (SNAP) trial, wherein the SCA prevented weight gain in a large sample of young adults with overweight over 3 years.”

It’s worth noting that this earlier study involved young people with BMI in the range of 21 to 30 – not in the range of obesity.

So, while there’s nothing wrong ever with making small changes in health behaviors, our takeaway is that a person who wants to overcome obesity can’t count on this to turn the tide.

Obesity is, after all, a medical problem in which the physiology of adipose tissue isn’t working quite right. Good behavior isn’t futile, but it’s usually not enough to overcome obesity all on its own.

Click here for the study in CMAJ and here for the SNAP trial.

Small Bust of a Young Girl, painting by Odilon Redon / WikiArt

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May 30, 2022