Four Effective Weight-Loss Programs . . .

Summarized by Robert W. Griffith, MD
June 19, 2006

Summary

Four commercially available weight loss programs, if followed for 6 months, are all effective in reducing weight by about 13 pounds, or 8%.

Introduction

Several comparisons of newer diets have been reported (see links below). They usually find that most diets have a short-term benefit in helping the individual lose weight, but long-term success is rare - 50% of weight loss is regained within a year or sooner. Now researchers in the UK have compared the effectiveness of four commercial weight loss programs, and reported their results in the British Medical Journal. Here's a summary of their findings.

What was done

The four popular weight loss programs studied were:

• Dr Atkins New Diet Revolution - a self-monitored low-carbohydrate eating plan
• Weight Watchers Pure Point Program - an energy controlled diet with weekly group meetings
• Slim-Fast Plan - a meal replacement approach
• Rosemary Conley's Eat Yourself Slim and Fitness Plan - a low-fat diet and weekly group exercise class.

Five regional centers throughout the UK participated, enrolling volunteers for the study who were identified through a BBC advertising campaign. The subjects had to have a body mass index (BMI) between 27 and 40, and be between 18 and 65. People with coronary heart disease, diabetes, kidney, liver, or respiratory disease were excluded. Participants could not be taking medications for high blood pressure or high cholesterol, or any drug for weight loss.

Three hundred people entered baseline testing - 60 at each center - allowing 60 people per weight loss program and 60 controls. The controls were asked to maintain their current diet and exercise program; they were offered any of the diet programs at the end of 6 months, free of charge.

Weight, height, waist size, blood pressure, and fasting blood and body fat were measured at baseline, 2 months, and 6 months. Fat was measured by whole body dual X-ray absorptiometry. No dietary or exercise advice as given so as not to influence the results for a particular group. Weight and dieting behavior was recorded after one year in all participants still available, to see what had happened during the 6 months after the study.

What was found

The average age of participants was 40; three-quarters of them were women. The average time spent on the allocated program was just over 24 weeks, showing that adherence to programs was high.

All the programs resulted in significant weight loss, which was high initially but then slowed. Average weight loss was greater in the early weeks for the Atkins Diet, compared to the other programs, but then it too slowed, and was the same as the others by the end of the 6 months. The average individual weight lost over the 6 months in all the programs was 13 pounds (5.9 kg).

Loss of body fat was similar to that for body weight. Again, loss on the Atkins Diet was greater initially, but slowed down and was similar to the other three programs by the end of the study. The average fat loss was 9.7 pounds (4.4 kg), or 3% of the original body fat. Values for the Slim-Fast Program lagged somewhat behind the other three groups, but not significantly.

Waist circumference was reduced by an average of 3 inches (7.5 cm). Slight blood pressure and fasting blood glucose reductions were seen for all programs, but were not statistically significant, except for a significant fall in glucose with the Weight Watchers program. Blood cholesterol levels fell initially in all groups except the Atkins Diet group, but the changes were negligible by 6 months.

After 6 months, there were 'clinically useful' reductions in percentage body weight as follows: Rosemary Conley 9.9%, Weight Watchers 9.0%, Atkins 8.9%, and Slim-Fast 6.8%. The control group had gained 0.95%.

After 12 months, over half the original participants returned information. Less than half of these were continuing with their allocated program - most of those on Weight Watchers or Rosemary Conley, and the least on Slim-Fast and Atkins, which were 'unsupported' programs.

What these results mean

The main finding of this study is that commercially-available weight loss programs can provide clinically relevant benefits - reduced body fat, smaller waist, and lower blood pressure, in addition to an average weight loss of 13 pounds over 6 months. It doesn't seem to matter which type of program is used, but those supported by weekly meetings appear to have a longer-lasting impact. How does this information from the UK help the US obesity problem? The researchers point out that the role of the BBC in recruitment may have influenced the success of the programs. Participants knew that they might be 'on TV' after several weeks on a diet, and so may have been better motivated to stick with the program.

All these studies comparing weight loss programs have produced evidence that successful approaches have one thing in common - reduce your energy intake and/or increase energy expenditure, and you will lose weight. This truth will eventually be found by overweight people who hop from one diet to another. There's no substitute for 'calories IN - calories OUT' as a mantra for weight control. If it helps to switch diets to avoid boredom, just as you change your exercise regimes, go ahead - they should still work OK.

Source

• Truby H, Baic S, deLooy A, et al. Randomized controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials". BMJ Online First posted 5/23/2006, bmj.bmjjournals.com

Related Links
Putting Low-Carb Diets to the Test
Dieticians Review Five Popular Diets
It's Not Which Diet, It's How You Diet

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