New research shows that eating calories may help you lose weight

Calories have always been assumed to be 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 idea, suggesting that the timing of calorie intake — and how calories are distributed throughout the day — may influence the effectiveness of weight loss.

These findings suggest that meal timing mismatched with your body’s circadian rhythm — the 24-hour cycle that regulates calorie burning, digestion, nutrient metabolism and other bodily processes — may contribute to weight gain in ways that exceed the number of calories you consume each day.

Now, two strictly controlled trials, both published this month in the journal Cell Metabolism, Support the theory that appropriate timing and daily calorie allocation may provide benefits for weight loss.

Here’s what to know about the latest research — and how the results may apply to you.

Big breakfast curbs hunger

One study, conducted by researchers from the University of Aberdeen in the UK, looked at whether eating a larger breakfast and a smaller dinner – or vice versa – leads to greater weight loss.

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

Four weeks later, the groups switched and followed the opposite diet.

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

Researchers provided all foods and drinks. Participants’ daily energy expenditure, resting metabolism, appetite, and weight loss were measured during the study.

Both regimens resulted in almost 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 did not affect appetite control. Eating a larger breakfast significantly reduced hunger and increased feelings of fullness during the day compared to eating a larger dinner.

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

Instead, they suggest that eating the largest meal of the day in the morning may contribute to weight loss over time by reducing appetite and thus reducing calories.

Eating late increases hunger and reduces calorie burn

Previous research has shown that eating later in the day is associated with an increased risk of obesity and poorer success in weight loss, findings that cannot be explained by differences in calorie intake or physical activity.

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

The laboratory trial included 16 healthy, overweight or obese adults who completed two six-day diet protocols: an early eating protocol with meals at 8 a.m., noon, and 4 p.m. and a late eating protocol with the same set meals at noon, 4 p.m. and 8 pm

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

The researchers measured feelings of hunger and appetite, and levels of appetite-regulating hormones and calories burned. They also studied the activity of genes in adipose tissue.

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

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

The researchers note that the increased motivation to eat observed with late eating may be more pronounced in a real-world environment where people can eat as much and as much as they like.

Limitations and Effects

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

It remains to be established whether the reduced appetite associated with eating a larger breakfast translates into lower calorie intake, or if this effect depends on the timing of the evening meal.

However, these findings are intriguing and may give you pause to skip breakfast and/or eat a late dinner.

If you are limited-time dining, they may ask you to change your eating window from evening to morning or afternoon.

Leslie Beck, a Toronto-based private dietitian, is Medcan’s director of food and nutrition. Follow her on Twitter Tweet embed

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