Delaying mealtimes associated with greater insulin resistance

Key takeaways:

• Insulin resistance was greater under circadian misalignment conditions vs. circadian alignment conditions.
• The researchers plan to evaluate potential effects of delaying mealtimes in a free-living environment.

BOSTON — Delaying mealtime 5 hours after waking resulted in greater insulin resistance vs. delaying mealtime by a single hour, research presented at NUTRITION found.

According to Marie-Pierre St-Onge, PhD, FAHA, CCSH, an associate professor of nutritional medicine at Columbia University, and colleagues, delayed mealtimes can disrupt natural day and night cues, causing a circadian misalignment (CM).

CM has previously been linked to negative metabolic and anthropometric outcomes, so the researchers set out to investigate potential underlying mechanisms.

“In this study, we randomized participants in a crossover design to maintain adequate, stable sleep and we had them eat early relative to their wake time,” St-Onge told Healio.

The crossover trial involved two 44-day phases, with one taking place under CM conditions and the other under circadian alignment (CA) conditions.

Both phases consisted of 15 days of energy-matched controlled eating, which was then followed by 4 weeks of ad libitum eating. In addition, both phases had an eating window of 10 hours and a sleep period between 11:30 p.m. to 8:00 a.m. However, the CM phase’s eating window started 5 hours after waking, whereas the CA eating window began 1 hour after waking.

The cohort included four men and four premenopausal women with a mean age of 36 years and BMI of 28.8 kg/m². Additionally, 62.5% were nonwhite individuals.

Insulin outcomes were measured with the homeostasis model assessment of insulin resistance, or HOMA-IR.

The researchers reported finding “a significant main effect of condition” (P = .021). The mean HOMA-IR values were 2.49 for CA conditions and 3.19 for CM conditions over the study period.

St-Onge highlighted the fact that the results were observed in an acute setting and over a prolonged period.

“There was no day by condition interaction. The findings were stable over time,” she said.

St-Onge suggested that primary care physicians “talk to their patients about eating early and ending their mealtimes early.”

“If you’re having an eating pattern that’s reminiscent of breakfast skipping, for example, and then keeping that same eating window and delaying toward the evening hours, it may have adverse effects on insulin resistance,” she said.

Moving forward, St-Onge said “we’re now looking at evaluating what the effects are in a free-living condition, not in a controlled condition.”

“Here, the meals are identical in both conditions, so we know that the impact is solely due to the timing of eating,” she said. “But we also know that when people eat a little later in the day, they tend to have different types of foods, and by looking at this after an ad libitum eating occasion, we’ll be able to see if there’s a compounded effect of an adverse diet that’s associated with eating later.”