Grazing vs Two Large Meals—Which is better for Insulin Sensitivity?

New study suggests that eating two large meals per day improves insulin sensitivity and promotes weight loss better in patients with type 2 diabetes than grazing

Conventional dietary wisdom holds that eating frequent but small meals—“grazing”—helps to maintain steady blood glucose and promotes weight loss. New research from the Czech Republic calls that theory into question. The study suggests that eating two large meals per day improves insulin sensitivity and promotes weight loss better in patients with type 2 diabetes than grazing, even when the total number of daily calories is the same.

“The data suggest that eating fewer, larger meals—a hearty breakfast and lunch—can be healthy and beneficial for people with type 2 diabetes,” said Hana Kahleova, MD, PhD, researcher at the Institute for Clinical and Experimental Medicine in Prague. “Our results support the ancient proverb, ‘Eat breakfast like a king, lunch like a prince, and dinner like a pauper.’”

The randomized, crossover study included 54 adults with type 2 diabetes (average age, 59). Patients were assigned eating plans designed to cut their intake by 500 calories per day for 24 weeks. Participants had well-controlled diabetes, with an average A1c of 7.2%, but were overweight, with an average body mass index (BMI) of 32.6. Before beginning their new eating plans, the patients participated in group meetings and received individual counseling, noted Dr. Kahleova, who recently presented the study results at the American Diabetes Association’s 73rd Scientific Sessions in Chicago.

For 12 weeks the participants ate 6 meals per day—breakfast, lunch, dinner, and three snacks. For the other 12 weeks they ate only a large breakfast between 6:00 and 10:00 a.m. and a large lunch between 12:00 and 4:00 p.m. Macronutrient ratios were the same for both plans, at 50-55% carbohydrate, 20-25% protein, and 24-30% fat.

At the beginning of the study and at 12 and 24 weeks, the researchers assessed the participants’ insulin secretions via c-peptide convolution and measured the participants’ insulin sensitivities via glucose clamp. The participants also underwent scans to determine the amount of fat in their livers.

Study Results

The investigators found that insulin secretion increased comparably in both regimens. Insulin sensitivity improved and the amount of fat in the participants’ livers decreased with both regimens, but more so when the participants ate only two meals per day.

Participants also lost more weight when eating just two meals per day, an average of 8.2 pounds, compared to just over 5 pounds with six meals per day. This difference was reflected in BMI, as well, with an average decrease of 1.23 points in BMI compared to .82 points when eating six meals per day.

Eating only two large meals per day may not be for everyone. 

“Before addressing this with patients, it is important to first assess each individual’s eating pattern to see what would be a realistic change before making recommendations about meal and snack distribution,” said Linda M. Delahanty, MS, RD, LDN, Director of Nutrition and Behavioral Research at Mass General Hospital Diabetes Center in Boston, Massachusetts.

Those wishing to follow a two-meal regimen might do well by making dietary changes slowly, Ms. Delahanty added. “A first step may be to encourage no evening snacks after a large dinner so that there may be a longer time period of overnight fasting. If a patient skips grazing or snacking at night after dinner, it will likely reduce overall calorie intake, enhance weight loss, and may result in more of an appetite to eat some breakfast the next morning.”

Ms. Delahanty stressed that clinicians should take care to address their patients’ diabetes care regimens. “Certainly, in people with type 2 diabetes, the diabetes medication or insulin regimen would need to be considered and possibly adjusted before adopting this type of eating pattern to avoid problems with hypoglycemia.”


Disclosures

Dr. Kahleova and Ms. Delahanty disclosed no conflicts of interest.

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