A recent edition of the Arbor Clinical Nutrition Updates (September 2006) reviewed the results obtained from four different weight-loss diets in the so-called "BBC Diet Trials".
It's not often that TV programmes get mentioned in scientific publications, but this public effort to compare the success of various popular weight-loss regimens has not only produced results that scientists can use, but the findings were also published in the prestigious British Medical Journal (BMJ) in June this year.
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The results of this comparison make for fascinating reading and most individuals who need or want to lose weight should take note of the findings.
The study
The BBC organised that the 293 obese adults (with an average BMI = 32 at the start of the diet trials) would use four different diet and weight-loss regimens for six months to lose weight.
The following diets were used:
Dr Atkins New Diet Revolution – high-protein, high-fat with very little carbohydrate.
Weigh Watchers Pure Points Programme – a balanced, reduced-energy diet with dietary counselling.
The Slim-Fast Diet – a very low-energy diet with two meals a day replaced by diet shakes.
The Rosemary Conley Eat Yourself Slim Diet and Fitness Plan – a low-fat, balanced diet with weekly group exercise classes.
Participants were assigned to one of these diets randomly and their weight loss was monitored over a period of six months. A control group that did not diet was also included.
Outcomes
The researchers, who tracked the success or failure of these four diet programmes, looked at the following outcomes:
How much weight loss did each of the four diets produce?
What percentage of participants managed to last for six months?
Did these diets have a positive effect on blood pressure, blood glucose and/or blood fat levels?
Results 1) Average weight loss
All four diet groups experienced significant weight loss compared to the control group in the six-month period.
After one month, the dieters had lost the following amounts of weight:
Atkins diet – 4,4kg
Weight Watchers – 2,9kg
Slim-fast – 2,7kg
Rosemary Conley – 3,2kg
In comparison, the control group only lost an average of 0,5kg.
After 6 months, the dieters had lost the following amounts of weight:
Atkins diet – 6,0kg
Weight Watchers – 6,6kg
Slim-fast – 4,8kg
Rosemary Conley – 6,3kg
In comparison, the control group had gained weight!
It is interesting to note that dieters using the Atkins diet lost significantly more weight than the other dieters in the first month. However, after six months this diet was no more or less successful than the other diets!
These results also show that Weight Watchers and the Rosemary Conley regimen of diet and exercise produced the best results, while the use of shakes to replace two meals a day in the Slim-fast regimen did not achieve as much weight loss in six months (i.e. 4,8kg vs. more than 6kg).
2) Adherence
One of the measures of a good weight-loss regimen is if users can stick to it for long periods to achieve their goals. Seventy percent of the participants using the Atkins, the Slim-fast and the Rosemary Conley diets managed to stick to their diets for six months, but for those using the Weight Watcher diet, 81% completed the six-month trial. This indicates that the Weight Watchers approach improves adherence and is probably the easiest diet to maintain.
3) Biochemistry
There were no significant differences in blood pressure or blood cholesterol levels between the four diets. Glucose levels were, however, lower in the Weight Watchers group, which is another plus for this sensible, easy-to-follow diet regimen.
Commercial diets can be useful
The Arbor Clinical Updates (2006) point out that two-thirds of Western adult populations "watch their weight". If this is indeed true, it was significant that this BBC study was carried out with popular commercial diets, giving us an indication of whether the billions of dollars, pounds and Rand spent on such diets make a difference in terms of weight loss.
Which diets were best?
Although all four diets produced weight loss in a six-month period, it is evident that dieters using the Weight Watchers' approach lost the most weight and had the lowest drop-out rate.
If one adds to this the findings of a telephone survey of about 1000 Weight Watchers clients who had reached their goal weight, that 1/5 of all these participants maintained a weight loss of at least 10% of their original weight after five years, then the evidence that programmes such as Weigh Watchers can really make a difference, becomes more compelling.
The Arbor Clinical Updates (2006) also report on another follow-up study, which found that the best results for sustained weight loss for long periods were obtained when diets were combined with exercise.
The bottom line
So, what do the BBC Diet Trials show? That commercial diets can be successful and promote weight loss, but that diets which are difficult to follow, such as the Atkins diet with its high protein and fat content, or the Slim-fast diet that uses diet shakes to replace meals, do not produce as much long-term weight loss as the more balanced approaches such as Weight Watchers and the Rosemary Conley Eat Yourself Slim Diet and Fitness Plan.
It stands to reason that most people will find it difficult to not only reduce their energy intake, but also use an eating plan that deviates from our normal dietary intake. Diet programmes that combine normal foods and exercise are much more likely to improve adherence and results.
So, think carefully about the diet or weight-loss regimen you choose, because your choice could make the difference between success and failure. – (Dr Ingrid van Heerden, DietDoc, November 2006)
References:
(Arbor Clinical Updates (2006), Issue 261;1-3; Truby et al, (2006). Randomised, controlled trial of four commercial weightloss programmes in the UK: initial findings from the BBC 'diet trials', British Medical Journal, Vol 332(7553):1309-14 ).
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