American Association of Clinical Endocrinologists Annual Meeting
American Association of Clinical Endocrinologists Annual Meeting
May 17, 2018
3 min read

Meal replacements facilitate safe, effective weight loss

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Scott D. Isaacs
Scott D. Isaacs

BOSTON — As part of a very low-calorie diet, energy-controlled bars, shakes, soups or other products designed to replace meals can offer patients greater and faster weight loss than meal plans based on regular food, according to a speaker at the American Association of Clinical Endocrinologists annual meeting.

“Meal replacements allow for a structured eating pattern, reducing decision anxiety and making the diet easier to follow and stick to,” Scott D. Isaacs, MD, FACP, FACE, endocrinologist and obesity specialist at Atlanta Endocrine Associates, told Endocrine Today. “Meal replacements are portion controlled, low calorie, require minimal preparation and eliminate meal planning.”

Despite the negative publicity for very low-calorie diets resulting from Oprah Winfrey’s famous 67-pound weight loss on such a plan in 1988 — followed by regain of all the weight 2 years later — Isaacs said he commonly prescribes these programs, which aim to reduce caloric intake to less 800 kcal/day or less than 50% of resting energy expenditure.

“These diets are safe and effective, and they can be used and are helpful for long-term weight loss,” Isaacs said during the presentation.

Greater weight loss

Very low-calorie diets are typically composed of about 70 to 100 g per day of high-quality protein, about 80 g carbohydrate and 10 g to 15 g fat. Users also take a daily multivitamin supplement, because meal replacements may not include all recommended daily allowances, as well as a potassium supplement.

“There are a number of studies that show that meal replacements provide superior weight loss compared to regular-food diets, with improved weight maintenance at 2 years,” Isaacs said.

People with obesity often greatly underestimate the amount of calories they consume, Isaacs said, and meal replacements offer controlled portion sizes of low-calorie, filling foods. The lack of variety often decreases appetite and simplifies food choices.

Perhaps even more important, very low-calorie diets cause rapid initial weight loss, which is associated with long-term success.

“Fast weight loss is better than slow weight loss,” Isaacs told Endocrine Today. “Early weight loss predicts long-term weight loss. Patients with greater initial weight loss lose more weight and keep it off longer than those that lose it slowly. Slow weight loss is frustrating, but fast weight loss is motivating, which keeps the weight going down.”

The minimum duration for a vary low-calorie diet is 2 to 4 weeks; 12-week programs are typical. Isaacs describes the program as a “jump start” to the long-term goal. However, longer programs of 24 to 52 weeks can be safe, Isaacs said. Transitioning back to regular food should occur over 4 to 8 weeks but can be done in a shorter time.

Discussion of long-term weight maintenance begins at the first visit, Isaacs said, and depends on ongoing support and follow-up.

Medical monitoring

Very low-calorie diets require comprehensive management, including lifestyle modification and health education, coaching and weekly support. Close medical monitoring is also required, Isaacs said.

Contraindications for a very low-calorie diet include renal insufficiency, advanced liver disease, pregnancy or breast-feeding, a recent cardiovascular event, active malignancy, an eating or other severe psychiatric disorder, substance abuse, porphyria or serious medical illness. In addition, Isaacs does not prescribe very low-calorie diets for anyone aged younger than 18 years, but will manage less-extreme low-calorie diets with meal replacements for these patients.

Several medications require adjustment for patients on a very low-calorie diet, including diabetes drugs, beta blockers and other antihypertension drugs, diuretics, warfarin, digoxin and anti-seizure drugs.

For patients with type 2 diabetes, Isaacs stops sulfonylureas and often discontinues all oral diabetes agents on the first day of the very low-calorie diet. Basal and prandial insulins should be reduced by half or more, with continued monitoring, and patients warned about risk for hypoglycemia, Isaacs said. He monitors blood glucose weekly for those taking insulin.

For patients with type 1 diabetes, Isaacs recommends starting with a 10% to 20% reduction in basal insulin.

Anti-obesity drugs can be prescribed in conjunction with a very low-calorie diet at any point in the program, but Isaacs said he prefers to use them after the rapid weight-loss phase when patients are learning to maintain their weight loss.

Weight-loss success

Compliance is key to success with very low-calorie diets, and so there is high variability in amount of weight loss among patients on these programs, Isaacs said. But patients who stick with the diets can lose substantial amounts; Isaacs said he has had many patients who have lost more than 100 pounds and two patients who lost 200 pounds.

“For the patients who have a lot of weight to lose, this is definitely something to consider,” Isaacs said. “They can lose 15% to 25% of their body weight in 3 to 4 months.” – by Jill Rollet


Isaacs SD. Effective Use of Meal Replacements for LCDs and VLCDs. Presented at: AACE Annual Scientific and Clinical Congress; May 16-20, 2018; Boston.

Disclosure: Issacs reports he has consulted for ABC Television Network and has been a speaker for Novo Nordisk and Orexigen.