We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book.
Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres. The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values one participant was not used in this analysis as she withdrew because of pregnancy.
A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data baseline, two months, and six months.
Analysis of variance showed that the test centre did not affect total weight loss in participants who completed.
Attrition rates did not differ between centres, so we analysed data from all participants together. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. Table 1 shows the baseline demographics and anthropometric measures. The mean time spent on the diet was Mean baseline characteristics of participants in the BBC diet trials allocated to different diet regimens.
Values are mean SD. Monthly weight loss by using all available data fig 2 was high initially but then slowed. At other time points, mean weight loss did not vary significantly between the diet groups table 2.
Intention to treat analysis of main outcome indicators in participants in the BBC diet trials allocated to different diet regimens. Loss of body fat showed similar patterns table 2. In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group.
Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss kg and percentage slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group.
All diets resulted in a reduction in waist circumference. We found few significant differences in cardiac risk factors between the diets groups and the control group table 3. Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group.
Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure adjusted R 2 0.
Intention to treat analysis of changes in cardiac risk factors in participants in the BBC diet trials allocated to different diet regimens. Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group by 0.
A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. Figure 3 shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight fig 3.
After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.
These losses were achieved despite the random allocation of diets. Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.
Older participants were significantly more likely to complete than younger ones mean age No differences in diet, centre, or sex were found between participants who completed or withdrew. Participants in the control group who had switched to dieting mean weight loss 6. Mean SD weight loss for participants in the BBC diet trials who completed 12 months on the diet to which they were randomly allocated. Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss.
The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone.
The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested. The range of absolute weight loss in participants who completed the study was wide.
Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies.
Though clinical trials are conducted by experts and always regulated by agencies that ensure the safety of all participants, you should always know that there is an inherent risk in participating in any kind of research study. Clinical trials associated with diet, nutrition, or weight loss may involve anything from taking a medication to eating a certain diet, so it is important to understand what are the components of the study and if you are willing and capable to do it before you make the commitment.
However, clinical trials are always voluntary, so you are free to withdraw your participation at any point in time without any consequences. When you agree to participate in a clinical trial you will sign an informed consent document stating that you understand and agree to participate in the study. This directory of weight loss clinical trials includes all weight loss clinical studies in the ClinicalTrials. To add a study to our list, contact us.
Virtually all Americans are affected by the health issues caused by weight or know someone who is. Start Matching. Weight Loss Methods and Lifestyle Changes. Current Weight Loss Clinical Trials Though clinical trials are conducted by experts and always regulated by agencies that ensure the safety of all participants, you should always know that there is an inherent risk in participating in any kind of research study.
Content Box. All rights reserved. Publication types Randomized Controlled Trial. Participants worked in collaboration with the dietitian to make improvements to their overall diet quality.
For example, increasing their weekly fish consumption, or swapping the occasional chocolate ice-cream for natural yoghurt with walnuts and a drizzle of honey.
After three months, participants attended a Follow Up Appointment where they completed all of the same measures they had completed at Baseline.
By comparing to Baseline results, the research team can make comparisons on whether the befriending or diet group had greater improvements to their depression symptoms. Lastly, participants were followed up via telephone calls six months after their Baseline appointment to once again assess their diet and mental health. The results of the study, published in the international journal BMC Medicine , showed that participants in the dietary intervention group had a much greater reduction in their depressive symptoms over the three-month period, compared to those in the social support group.
At the end of the trial, a third of those in the dietary support group met criteria for remission of major depression, compared to 8 percent of those in the social support group. These results were not explained by changes in physical activity or body weight, but were closely related to the extent of dietary change.
In other words, those who improved their diet the most experienced the greatest benefit to their depression.
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