The Limits of Active Living in Obesity Management

Increasing physical activity and reducing sedentariness (not quite the same) are good for you – no doubt about that.

Also, people at any weight will reap benefits from being more active and less sedentary – so this is really for everyone – not just for those with excess weight.

That said, when it comes to actually losing weight, as regular readers will be well aware, increasing physical activity is perhaps not the most effective intervention – in the end – fewer ‘calories in’ will always beat more ‘calories out’ as a strategy for weight loss.

It is therefore perhaps not surprising, that a randomized controlled trial by Robert (Bob) Ross (Queen’s University, Kingston, Ontario) and colleagues, just published in the Archives of Internal Medicine, show a rather modest (statistical) reduction in abdominal obesity with an ‘active living’ intervention in sedentary obese adults.

This study specifically assessed the effectiveness of a 2-year behaviourally based physical activity and diet program aimed at reducing obesity implemented entirely within clinical practices (in Canada and the US).

A total of 490 sedentary, obese adults were randomized to usual care (n = 241) or to the behavioral intervention (n = 249), which included individual counseling from health educators to promote physical activity and a healthful diet.

According to the authors,

“The intervention included individually tailored counseling based on the transtheoretical model and social cognitive theory. Counseling was delivered by health educators who had degrees in kinesiology and who received behavioral counseling training from a clinical psychologist. Each health educator was assigned to 1 of 3 family medicine clinics and delivered all counseling sessions on site within a private office. Motivational interviewing served as the counseling model. During phase 1 of the intervention (months 0-6, 15 sessions), the health educator worked one on one with participants to provide knowledge and skills to increase daily physical activity and consume a healthful diet. Phase 2 (months 7-12, 6 sessions) started at session 16 and encouraged the participants to maintain their current program (45-60 minutes of activity per day and healthy eating patterns). During phase 3 (months 13-24, 12 sessions), contact with health educators continued, but the session duration was determined according to each participant’s WC value and physical activity level.”

Although 396 (81%) participants completed the trial, and both men and women attended 73.5% of the planned counselling sessions, the mean effect on waist circumference (the primary outcome measure) at 24 months, was -0.9 cm in the intervention group compared to +0.2 cm in the ‘usual care’ group. Notably, an effect on waist circumference at 24 months was evident only in men but not in women.

Although, one may have expected measurable benefits on other parameters even with no weight loss, there were in fact no significant difference in any of the measured cardiometabolic risk factors at the end of the 24 month trial period.

Despite trying to ‘spin’ these rather sobering findings in as positive a light as possible, the authors do admit that

“The principal finding from our study and others also reinforces the challenges inherent to the sustained adoption of healthy behaviors in today’s environment and suggests that the prevention of weight gain combined with modest reduction in WC during the 2-year study may reflect a more realistic expectation.”

As for the lack of cardiometabolic improvements (despite the statistically but perhaps not clinically significant reduction in waist circumference), the authors suggest this explanation:

“It is possible that the reduction in WC or body weight observed is below the threshold required for reduction in cardiometabolic risk. Alternatively, the lack of treatment effect may be explained by the observation that about 40% of our participants were taking medications to lower lipid levels or blood pressure, and baseline values were well within the clinically acceptable range.”

On a more positive note, at least numerically, patients in the intervention group had fewer hospitalizations for musculoskeletal (5 vs. 12) or cardiovascular events (9 vs. 18) than the ‘usual care’ group. Whether or not this translated into an overall health economic benefit is not known.

This study certainly supports the notion that achieving and maintaining significant weight loss with ‘lifestyle’ interventions alone (even with dedicated support as provided in this trial) remains a challenge – indeed people hoping to lose weight by simply being more active are likely to be disappointed (and unfortunately, likely to abandon their efforts, despite all the other benefits of physical activity).

Perhaps it really is time to move beyond ‘diet and exercise’ in obesity interventions – whether in primary care or elsewhere.

AMS
Edmonton, Alberta

Ross R, Lam M, Blair SN, Church TS, Godwin M, Hotz SB, Johnson A, Katzmarzyk PT, Lévesque L, & Macdonald S (2012). Trial of Prevention and Reduction of Obesity Through Active Living in Clinical Settings: A Randomized Controlled Trial. Archives of internal medicine PMID: 22371872

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