Low-Cal Diet With a Daily Meal Shake May Suit Some T2D Patients

Marlene Busko

April 04, 2019

Overweight or obese patients with type 2 diabetes who followed a diet with shakes to replace some meals for about 6 months lost 5 pounds more than their peers on a conventional low-calorie diet in a new meta-analysis.

Moreover, most patients in the liquid meal replacement study group only replaced 20% of their daily caloric intake (about 300 calories [kcal] or one meal) with a shake.

This review of nine randomized controlled trials by Jarvis C. Noronha, MSc, St. Michael's Hospital and University of Toronto, Ontario, Canada, and colleagues was published March 28 in Diabetes Care.  

"Despite not replacing a lot of calories, [the liquid meal] did help people achieve a lower calorie [intake] that resulted in greater weight loss" plus improved systolic blood pressure, senior author John Sievenpiper, MD, PhD, St. Michael's Hospital and University of Toronto, told Medscape Diabetes & Endocrinology.

However, "we don’t want to [oversell] these data," he stressed. "Unfortunately, in nutrition...you publish a single study and it's like 'This is it; this is the thing that's going to save you or kill you.' But the reality is this is just one more [option]," he said.

The meta-analysis found that liquid meal replacements "do work to help achieve weight-loss goals [in patients with diabetes]," he said, "and that weight loss does come with some downstream...benefits."

However, "in no way is this a head-to-head comparison against every strategy," Sievenpiper emphasized.

"So, you can't say that this is better than a Mediterranean or a DASH [diet] or a low glycemic index [diet] or any other intervention that we might want to use in our [overweight] patients with diabetes."

"It's just one more [strategy of many] that we can add to the toolbox...just one piece of that puzzle."

Meal Shakes for Weight Loss in Diabetes?

Sievenpiper notes that, in the Look AHEAD trial, "the largest comprehensive intervention with lifestyle in people with type 2 diabetes," the multifactorial intensive lifestyle intervention — which included the possible use of liquid meal replacements — helped people achieve the 7% weight loss goal and improved nephropathy, obstructive sleep apnea, and glycemic control.

And the American Diabetes Association, Diabetes Canada, and Diabetes UK include liquid meal replacements as an option for diabetes management in their clinical practice guidelines.

The current review was commissioned by the Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD) to update their guidelines.

"We've also published some reviews already on a vegetarian diet, Portfolio diet, and DASH diet," Sievenpiper explained, "and then we are going to put them all together into a position statement of our diabetes and nutrition study group of the EASD."

The researchers identified nine trials conducted in Asia (four trials), North America (three), Europe (one), and Australia (one) in which 961 overweight/obese people with type 2 diabetes were randomized to low-calorie weight-loss diets, with or without liquid meal replacements, for a median of 24 weeks (12 to 52 weeks).  

Participants were a median age of 55 years and 52% were women; they had a mean body mass index (BMI) of 30.5 kg/m2 and a mean HbA1c of 7.6%.

Participants in the liquid meal replacement groups received Glucerna SR (four trials), SlimFast (two), Medifast (one), Probiotic Formula WL (one), and Microdiet (one), which gave them an estimated 1500 kcal/day with a median intake of 48% carbohydrates, 30% fat, and 20% protein.

Participants in the comparison low-calorie groups were given a food exchange system (four trials), instructed to select low-calorie foods (4), or given a diet book (1) to provide them with a diet of an estimated 1500 kcal/day consisting of a median intake of 55% carbohydrates, 25% fat, and 17% protein.

In five of the nine trials, participants also received group education and counseling, which, Sievenpiper noted, reflects real-world practice.

Participants who received the liquid meal replacements had significant improvements in body weight (–2.37 kg), body fat (–1.66%), BMI (–0.87 kg/m2), HbA1c (–0.43%), fasting glucose (–0.63 mmol/L), systolic blood pressure (–4.97 mm Hg), and diastolic blood pressure (–1.98 mm Hg), compared with those on the traditional low-calorie weight loss diets (all P < .001).

And compared with the control low-calorie groups, they also had lower waist circumference (–2.24 cm; P = .003) and fasting insulin (–11.83 pmol/L; P = .04).

There was no effect on blood lipids.

The overall dropout rate was 18% in the groups with meal replacements and 20% in the control groups.

Weight Loss Diets Must Be Individualized

As a comparison, the Diabetes Remission Clinical Trial (DiRECT) trial had a much more severe caloric restriction, where participants received only liquid meal replacements with about 850 kcal/day for 3 to 5 months, which resulted in a high rate of remission of type 2 diabetes for many of those able to stick with the diet. Two-year results from this study were recently reported and showed just over a third of patients were in remission at that stage.

Weight-loss diets need to be individualized, Sievenpiper stressed. "None of the guidelines suggest that meal replacements are the be-all and end-all."

"We reviewed the evidence carefully and asked the question: Is it a strategy that we could consider? The answer is yes, there is some evidence of advantages, where people, if it fits with their values and preferences, might actually derive some benefit."

However, the studies in the meta-analysis did not look at weight-loss maintenance.

And "the overall certainty of the evidence was low to moderate owing to imprecision and/or inconsistency," the researchers write. "More high-quality trials are needed to improve the certainty in our estimates."

The meta-analysis was funded by the Diabetes and Nutrition Study Group of the European Association for the Study of Diabetes, Canadian Institutes of Health Research through the Canada-wide Human Nutrition Trialists' Network, and the Diet, Digestive Tract, and Disease Centre through the Canada Foundation for Innovation, and the Ministry of Research and Innovation's Ontario Research Fund. Six of the original trials were funded by industry; the other three were funded by other sources. Sievenpiper has reported receiving research funding or travel or consulting fees from multiple food companies including Abbott Nutrition and Nestle. Complete disclosures of all authors are listed with the article.

Diabetes Care. Published online March 28, 2019. Abstract

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