When you eat your calories may help weight loss, new research shows

It’s long been assumed that calories are calories, and when it comes to weight loss, it doesn’t matter when you eat them during the day.

However, recent studies have challenged this notion, suggesting that the timing of calorie intake, and how you distribute your calories throughout the day, may influence the effectiveness of weight loss.

These findings imply that meal timing that doesn’t match your body’s circadian rhythm (the 24-hour cycle that governs calorie burning, digestion, nutrient metabolism, and other bodily processes) may contribute to increased weight in ways that go beyond the number of calories you eat each day.

Now, two rigorously controlled trials, both published this month in the journal Cell Metabolism, lend support to the theory that proper timing and daily calorie allocation may offer weight loss benefits.

Here’s what you need to know about the latest research and how the findings might apply to you.

A bigger breakfast curbs hunger

One study, conducted by researchers at the University of Aberdeen in the UK, investigated whether eating a larger breakfast and smaller dinner, or the opposite, led to greater weight loss.

Thirty overweight or obese participants were assigned to one of two diets: Half consumed most of their daily calories (45 percent) at breakfast, fewer at lunch (35 percent), and fewer at dinner (20 percent). hundred). The other group consumed 20 percent of their daily calories at breakfast, 35 percent at lunch and 45 percent at dinner.

After four weeks, the groups switched and followed the opposite diet.

Calories (1,700 per day), diet composition (eg, protein, carbohydrate, fat), and meal frequency were matched for both diets; the only difference was the calorie load at breakfast or dinner.

The investigators provided all food and beverages. Throughout the study, participants’ daily energy expenditure, resting metabolism, appetite, and weight loss were measured.

Both diets resulted in nearly identical weight loss after four weeks (seven pounds). There was also no difference in daily calorie burn or resting metabolism between the two groups.

Calorie distribution affected appetite control. Eating a larger breakfast resulted in a significant reduction in hunger and greater satiety throughout the day compared to a larger dinner.

These findings contradict previous studies that suggested eating a large breakfast and light dinner helps people burn more calories.

Instead, they imply that eating the largest meal of the day in the morning may contribute to weight loss over time by decreasing appetite and thus calorie intake.

Eating late increases hunger, reduces calorie burn

Previous research has shown that eating late in the day is linked to a higher risk of obesity and less success in weight loss, results that could not be explained by differences in calorie intake or physical activity.

For the second study, researchers at Brigham and Women’s Hospital in Boston set out to determine how eating late might influence obesity risk.

In the lab experiment, 16 healthy overweight or obese adults completed two six-day diet protocols: an early feeding protocol with meals at 8 a.m., noon, and 4 p.m., and a late feeding protocol with exactly the same scheduled meals. at noon, 4 pm and 8 pm

Physical activity, posture, sleep, and light exposure were strictly controlled.

The researchers measured perceived hunger and appetite, levels of appetite-regulating hormones, and calorie burn. They also looked at gene activity in adipose tissue.

Late eaters were twice as likely to report hunger during the day as early eaters. Levels of leptin, a hormone that indicates satiety, were reduced during the late feeding protocol compared to the early feeding protocol.

When the participants ate later, they also burned, on average, 60 fewer calories per day than when they ate earlier. Among the late eaters, gene activity in adipose tissue showed changes indicating increased fat storage and decreased fat burning.

The researchers noted that the increased urge to eat observed with late eating may be even more pronounced in a real-world setting where people can eat as much and as often as they want.

Limitations, Implications

Both studies were small and of short duration. It is not known, for example, whether the observed effects of eating late would persist over time.

And it remains to be seen whether the reduced appetite associated with a large breakfast translates into lower calorie intake, or whether this effect depends on the timing of dinner.

Still, these findings are intriguing and may have you stopping to skip breakfast and/or a late dinner.

If you are time-restricted eating, you may be instructed to change your eating window from overnight to morning or afternoon.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD