Predictors of weight loss readiness

In an article published in the Journal of Behavioral Medicine, Teixeira et al followed 112 overweight or obese middle-aged (avg age = 47.8 years, and just under half were postmenopausal) for the first four months of the beginning of a two year weight loss intervention program.

The article is old – from 2002 – but I think its relevance remains timely, especially as we still, of course, have tons of people trying to lose weight, tons of people being unable to (particularly in the long-term), and tons of people dropping out of programs. Thus, finding out what affects successful and unsuccessful results is extremely important and a constant area of inquiry.

While no study is exhaustive, this study on “psychosocial predictors of success for behavioral weight reduction” included so many questionnaires and measures of data. They measured:

·        Weight (at two points)

·        Body fat and BMI (props to the researchers for using a DEXA scan, one of the most, if not the most, reliable ways of measuring body fat)

·        Physical activity (at baseline and at the end)

·        Number of recent diets

·        Number of years at current weight

·        Recent weight losses

·        Frequency of having about a 10 lb fluctuation in weight

·        The affect his/her weight has on his/her “health, social and interpersonal life, work, mobility, self-esteem, sexual function, activities of daily living, and eating in the past week”

·        General social support

·        Depression

·        Self-esteem

·        The tendency to “persevere, finish tasks initiated, maintain self-discipline, and motivate oneself”

·        Whether the participant is a binge eater and if the severity of the binges related to emotions, thoughts, and behavioral manifestations

·        Efficacy to control overeating and weight management

·        “Cognitive (eating) restraint, eating disinhibition, and perceived hunger”

·        Dieting and weight loss readiness and motivation

·        Self-efficacy for exercise for at least 6 months in several situations

·        Exercise perceived barriers to habitual physical activity

·        Exercise-specific support from family and friends over the past 3 months in terms of involvement and rewards/punishment

·        Concern with body image

·        Body size dissatisfaction

·        Feelings towards various parts or characteristics of a subject’s body and body function

See, tons of measures!

In short, they assessed eating- and exercise related behaviors, body image, quality of life, weight and dieting history, weight outcome evaluations and expectations, mood, self-esteem and self-motivation.

The subjects were divided into four groups, all receiving the same treatment, which included seeing an intervention team for a 50-min hour every week, being provided with information on physical activity, nutrition, psychology, behavioral modification, and overall healthy lifestyles and weight loss, being encouraged to lower cals and increase activity resulting in a 300-500 calorie deficit, the recommendation of losing about .5 kg a week, CBT-esque training regarding self-monitoring, enhancement of self-efficacy, relapse prevention, contingency management, and social support. Goals were individualized and tailored to the individual subject.

At the end they broke down the groups into 3 based on weight loss, with the first/highest/successful group losing about 6.4 kg, and the last/lowest/least successful losing 1.9 kg or less.

Compared to the most successful group, the least successful group had a greater amount of diet attempts and recent weight losses, a higher degree of body dissatisfaction, more strict weight outcome evaluations, higher perceived impact of weight on work and lower self-motivation.

Some of the greatest associations to and predictors of weight loss, both positive and negative, were having had more diets in the previous year, having higher weight loss expectations, having more self-motivation (perceived confidence to meet set goals, finish tasks started and persevere in spite of difficulties) and having less body size dissatisfaction. Other strong predictors were the number of years at the subject’s current weight, a high perceived impact of weight on health and work, the “obstacles” subscale of exercise perceived barriers and the “making time” subscale of self-efficacy. These were independent predictors.

Other studies have also shown recent and repeated diet attempts and body size dissatisfaction as some of the strongest predictors of weight loss, suggesting that these predictors may be some of the most consistent in successful weight loss.

When subjects believe their weight is responsible for a lower quality of life, they may be more likely to fail at initial attempts at weight loss.

The authors noted that one of the more interesting findings was that subjects who had more grandiose desires for their “acceptable” or “happy” weights lost significantly less weight than those who would be more okay with smaller losses.

Other findings included:

• 21% dropped out of the program (so 89 subjects completed it), and they were already losing less weight prior to dropping out.
• 63% expending less than 150 cals, which was the minimum recommendation, in physical activity at baseline, but at the end, 60% reported having met the goal of burning 1500 cal a week.
• Subjects’  “acceptable” weight at the end of the 4 months would be 75.9 kg.
• In order to get to their “happy” target weight for the 4 months, they would need to lose an average of 12.6 kg.
• More exercise and a higher rate of attendance both = increased weight and fat losses.
• Self-efficacy was not a predictor of weight loss.
• Self-efficacy regarding food, eating restraint, disinhibition, hunger and binge eating did not predict weight loss.
• Baseline scores of eating behavior did not predict changes in weight.
• A combination of independent baseline variables are better predictors than is any single one.

Teixeira et al propose including noncompleters in analysis, including psychosocial factors, to see if they have characteristics that predispose them to drop out and also to better be able to predict weight loss outcomes.

Finding predictors for readiness is important in order to best match interventions to individual patients, save resources, and best increase program efficacy.

As the authors state in the intro, “progress in eliciting short-term weight loss has not been met by a comparable improvement in weight management.” We need to learn more, predict better, and succeed in helping people lose weight for the long-term.

randi morse, randi.morse@gmail.com, newton, ma