The study, conducted by Dr. Erik Hemmingsson, Karolinska Institutet and Karolinska University Hospital Obesity Center, Stockholm, Sweden, and colleagues also found that participants were more likely to drop out if they received slightly more calories (the low calorie diet/LCD) than those on the rapid weight loss very low calorie diet (VLCD).
Findings from the study are currently being presented at the 19th European Congress on Obesity in Lyon, France.
In the program, participants are given the choice whether they would like to undergo rapid weight loss for the first three months or more moderate rate weight loss.
Those who select the VLCD consume 500 calories per day in the form of meal replacement shakes, while those who choose LCD consume 1200-1500 calories per day through meal replacement shakes, in addition to some healthy food. Participants of Itrim are also given home assignments, attend group sessions and engage in exercise. The 1 year Itrim program costs US$1300/€1000 per person.
The researchers examined 8,361 consecutively-enrolled participants. Of these participants 3,773 selected the VLCD (BMI 34±5kg/m2, 80% women; mean age 45 years), and 4,588 selected the LCD program (BMI 34±5kg/m2, 80% women; mean age 45 years). All participants received a diet and exercise maintenance program. 17% of participants were under 60 years of age, 31% were 50-59 years, 28% were 40-49 years, and 25% were under 40 years.
At the beginning of the program:
- 18% of participants were treated for hypertension
- 12% for depression
- 7% for abnormal body fats
- 8% for cardiovascular disease (CVD)
- 2% for cancer
- 3% for diabetes
- 1% for psychosis
After including dropouts, with the assumption that their body weight remained the same, the researchers found that the mean weight loss for the LCD group was 7kg (8% of body weight) and 12kg (12% body weight) for the VLCD group.
The researchers found that participants in the VLCD were 50% more likely to stay in the program than participants in the LCD group. Furthermore, those aged 40 years and under were 4.4 times more likely to discontinue the program than their counterparts aged 60+, 2.5 times more likely to drop out if they were between 40-49 years, and 13% more likely if they were aged between 50-59 years.
Participants in the VLCD group who started the program with a lower BMI were 60% more likely to drop out that those with the highest BMI.
In the VLCD group, the team found that depression increased the risk of dropout by 50% and psychosis by 2.6 times.
In the LCD group, they found that younger age (under 40 years) increased the risk of dropout by 2.6 times, depression 40%, and low BMI vs. highest BMI by 2.2 times.
The researchers found no association between cancer, treatment for CVD, diabetes, abnormal body fats, and hypertension with dropout rates. The team found comparable levels of dropouts among men and women.
Dr. Hemmingsson explained:
"While dropout was generally low, we noted an increased risk of dropout with low age, low BMI, depression and psychosis."
Health may be a factor which motivates older people more than younger ones, while the younger participants may find the more demanding program harder to follow because they have less free time, the authors believe.
"VLCD is pretty strict, although hunger is surprisingly not a problem after the first few days, and compliance with the diet is very good as reflected by the results. VLCD induces a very rapid weight loss, which is probably why the program works so well. Most people think that slow weight loss is preferable to rapid, but it is actually the other way around: rapid initial weight loss is associated with a larger long-term net weight loss. Make no mistake, however, it takes a lot of hard work to keep the weight off long-term."