August 16, 2018
In the latest study to report on a very low-calorie diet intervention, overweight men and women with prediabetes on a strict 8-week, 800 calorie/day meal replacement plan lost more than 10% of their initial weight.
However, men lost somewhat more weight than women; women tended to shed pounds around their hips whereas men lost more "heart harmful" weight around their middle.
Nevertheless, importantly, after the 8-week, rapid weight-loss diet, 35% of participants of both genders (and 40% of those who lost ≥ 8% of their starting weight) had normal glucose levels.
"I think this method of weight loss has a lot of advantages and should be given serious consideration for people with prediabetes or type 2 diabetes," coauthor Jennie Brand-Miller, PhD, professor of human nutrition and director, Glycemic Index Research Service at the University of Sydney, Australia, told Medscape Medical News in an email.
The patients don't have to "guess" what and how much to eat, and "the low drop-out rate (10%) tells us that the participants were happy to lose weight in this way."
"The rise in ketones in the blood during this low-calorie intake phase suppresses appetite," she explained.
"It's hard to make the commitment to start, but by day 3 to 4, participants are feeling satisfied and motivated," according to Brand-Miller. "They can see the weight loss for themselves."
This over 10% weight loss at 8 weeks was enough "to achieve major metabolic improvement in the first phase of a diabetes prevention program," said lead author Pia Christensen, PhD, of the University of Copenhagen, Denmark, in a statement.
Rapid Weight Loss to Try to Halt Progression to Diabetes
The PREVIEW lifestyle intervention study is the largest multinational study to investigate prevention of type 2 diabetes in overweight individuals with prediabetes, Christensen and colleagues write.
Participants entered an 8-week calorie-restriction phase to lose at least 8% of their weight; if they reached this target, they could enter a second long-term weight-loss maintenance phase (the results of which will be reported later this year).
Between 2013 and 2015, the trial enrolled 2224 adults at 8 sites in Europe, Australia, and New Zealand who were 25 to 70 years old with a body mass index (BMI) of ≥ 25 kg/m2 and prediabetes (based on plasma glucose levels or an oral glucose tolerance test).
Participants were a mean age of 52 years, had a mean weight of 100 kg (220 lb), and a mean BMI of 35 kg/m2. Most were white (88%), and about two thirds were women.
They were given meal replacement powder sachets for soups, shakes, and porridges, from the Cambridge Weight Plan (Northants, UK) and instructed to consume three sachets each dissolved in a cup of low-fat milk (250 mL) and one sachet dissolved in a cup of water each day.
They could also eat 375 grams (about a cup) of low-starch vegetables such as tomatoes, lettuce, and cucumbers.
This provided 810 calories/day: 44% from protein, 41% from carbohydrates, and 15% from fat.
Because the fiber content was low (13 g/day), participants were also advised to take psyllium fiber and drink enough water to avoid gastrointestinal side effects.
Participants had group meetings with a dietitian or counselor at weeks 2, 4, 6, and 8.
Gender Differences, But Average Weight Loss Over 10%
At the end of the first phase of the study, the 8-week, low-calorie eating regimen, men lost 16% more weight than women (11.8% vs 10.3%, respectively).
After adjusting for gender differences in weight loss, compared with women, men had larger reductions in metabolic syndrome Z-score, C-peptide, fat mass, and heart rate.
The authors caution that more research is needed to investigate whether the larger reductions of these parameters in women after rapid weight loss "is indeed beneficial or, rather, might compromise weight loss maintenance and future optimal/good cardiovascular health."
"Losing weight around the waist [as did the men] is more effective because it targets visceral fat (around the organs), while losing weight around the hips means losing subcutaneous fat [which is] less metabolically harmful," Brand-Miller explained.
"A decrease in HDL is not helpful/healthful but it often happens when people lose weight," she noted.
Women also lost twice as much fat-free mass as men (31% vs 16%, respectively), "which is striking," as men had a larger calorie deficit, the authors note. Based on their weight and low activity level, the men would have needed 3086 calories/day and the women would have needed 2353 calories/day to maintain their weight.
Men and women had similar improvements in insulin resistance.
Maintenance Results of PREVIEW to Be Presented This Fall at EASD
This kind of very low-calorie liquid meal-replacement diet is somewhat controversial, as many experts believe that individuals cannot maintain the weight lost when they eventually return to more normal eating patterns.
"Total meal replacements have been in use for more than a decade" Brand-Miller noted, and "this is a very safe and realistic way to lose weight fast," as the reconstituted foods contain the full complement of essential micronutrients.
The "800 calories is low, but it's the reason why weight loss was fast."
The PREVIEW study used the same meal replacement products that were used in the Diabetes Remission Clinical Trial (DiRECT), Brand-Miller said.
DiRECT was a year-long study in which people with type 2 diabetes consumed 850 calories/day for 3 to 5 months and then gradually reintroduced meals. The approach resulted in half of the participants going into remission; that is, they no longer had type 2 diabetes at the end of the study, as previously reported by Medscape Medical News.
The authors of DiRECT acknowledge that the big challenge is long-term avoidance of weight regain. Follow-up of DiRECT will continue for 4 years and, they said, will reveal whether weight loss and diabetes remission are achievable in the long term.
All eyes will look to the longer-term data from PREVIEW too.
"The results of the PREVIEW weight maintenance part will be announced at the [European Association for the Study of Diabetes annual meeting] in Berlin in October this year," said Brand-Miller.
Cambridge Weight Plan donated all products for the 8-week low-energy diet. Christensen received travel grants from Cambridge Weight Plan to attend scientific meetings unrelated to this article. Brand-Miller has reported no relevant financial relationships. Disclosures for the other authors are listed with the article.