When you eat could play an important role in weight loss, a new study suggests.

Researchers looked at the role of meal timing in 420 men and women in southeast Spain participating in a 20-week weight-loss treatment following several studies in animals showing a relationship between the timing of feeding and weight regulation.

"Our results indicate that late eaters displayed a slower weight-loss rate and lost significantly less weight than early eaters, suggesting that the timing of large meals could be an important factor in a weight loss program," Frank Scheer, director of the medical chronobiology program at Brigham and Women's Hospital in Boston, said in a release.

Of the participants, 51 per cent were early eaters who ate their main meal, lunch, before 3 p.m. The other 49 per cent had lunch after three.

The researchers found energy and nutrient intake, estimates of calories burned, appetite hormones and hours of sleep were similar between both groups.

"Nevertheless, late eaters were more evening types, had less energetic breakfasts and skipped breakfast more frequently than early eaters," Scheer and his co-authors wrote in Tuesday's issue of the International Journal of Obesity.

They suggested that new weight loss strategies should incorporate the timing of food as well as the classic look at calorie intake and distribution of carbohydrates, fats and protein.

Evening types or "night owls" like to stay up late at night and sleep late in the morning while early birds feel they perform best when they go to bed early and rise at dawn.

Timing has metabolic consequences

The researchers said that changes in these "chronotypes," genetic background and how the circadian system functions may be implicated.

Recently, fat tissue has been found to have an active circardian or body clock. The study's authors suggested that timing of feeding, for high energy meals in particular, could have metabolic consequences such as the development of obesity and weight loss.

A previous U.S. study showed that eating after 8 p.m. was associated with increased body mass index independently of sleep timing and duration.

In the study, late eaters had a lower estimated insulin sensitivity, a risk factor for Type 2 diabetes.

Study participants were given recommendations about the number of portions they should eat from each food group. They were free to eat those portions when they wished.

Most studies of shift workers also suggest they are more prone to obesity than day workers, even when they have the same energy intake, the researchers said.

The study was funded by grants from Tomás Pascual and Pilar Gómez-Cuétara Foundations, Spanish Government of Science and Innovation, Séneca Foundation from the Government of Murcia, the U.S. National Heart, Lung, and Blood Institute grants, U.S. National Institute of Diabetes and Digestive and Kidney Diseases, and the U.S. Department of Agriculture Research.

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  • Green Tea

    <strong>WHY IT WORKS:</strong> Green tea contains a type of antioxidant called catechins, which have been shown in studies to reduce body weight and waist circumference, says Haley Barton, family nutritionist of <a href="http://nutritionsavvy.ca/about-me/" target="_hplink">Nutrition Savvy</a>, based in Vancouver B.C. Green tea is also packed with cancer-fighting compounds that can benefit anyone’s diet, at any age.

  • Chili Peppers

    <strong>WHY IT WORKS:</strong> Chili peppers contain bioactive chemicals called capsinoids, Barton says. Studies have shown that the consumption of <a href="http://www.nutritionandmetabolism.com/content/7/1/65">capsinoids increased energy expenditure</a> (the amount of heat you produce internally and your external physical activity level) by 50 calories a day. Adding a bit of spice to your meals can also help reduce belly fat and appetite.

  • Coffee (Caffeinated Or Decaffeinated)

    <strong>WHY IT WORKS:</strong> Small amounts of caffeine have been shown to boost your metabolism through stimulation of your central nervous system, Barton adds. But make sure you're drinking the right amount. A cup of coffee (with about 150 mg of caffeine) is often enough to benefit from metabolic effects. Too much coffee, she adds, can lead to trouble sleeping, upset stomachs or irregular heartbeats.

  • Protein Foods

    <strong>WHY IT WORKS:</strong> The body experiences a significant elevation in metabolic rate right after eating a meal, called the “thermic effect of food," Barton says. In other words, our bodies need extra energy to digest, absorb and transport all the nutrients after consuming proteins. When you eat protein, Barton adds, it needs the most time to metabolize (at least 20 to 30 per cent of your body's energy). Eating fish, lean meats, eggs and plant protein like beans and soy will keep your metabolism accelerated for hours after your meal.

  • Iron-Rich Foods

    <strong>WHY IT WORKS:</strong> Iron is an essential mineral that helps transport oxygen to tissues throughout the body, Barton says. Iron also helps our bodies make energy — low iron levels can lead to fatigue, loss of appetite, anemia (not enough red blood cells) and slow down your metabolism. Foods rich in iron include oysters, mussels, beef, lamb, fish and poultry. Plant sources of iron include pumpkin seeds, lentils, tofu, chickpeas and other beans.

  • Vitamin D

    <strong>WHY IT WORKS:</strong> A study conducted last year showed that those with <a href="http://thechart.blogs.cnn.com/2012/06/25/vitamin-d-deficiency-may-cause-weight-gain/">low vitamin D levels gained more weight</a>, according to CNN.com. Barton adds there is still uncertainty as to how vitamin D contributes to weight management; however, studies have suggested low vitamin D levels may lead to fat accumulation. Looking for natural ways to get vitamin D? Get outside or eat some salmon.

  • Don't Starve

    <strong>WHY IT WORKS:</strong> The worst thing you can do to your metabolism is starve yourself. "Consuming a very low-calorie diet that robs your body of enough energy to satisfy its basic functions will plunge your metabolism into slow motion," she says. Ensure you're consuming at least 1,200 calories per day for women and 1,500 for men to meet your basic metabolic needs, she adds.

  • Eat Regularly

    <strong>WHY IT WORKS:</strong> Although research has given mixed results, one study showed that <a href="http://www.ncbi.nlm.nih.gov/pubmed/9780751">elderly women who ate two to three meals per day</a> were generally more overweight or obese compared to those who ate four to five meals or snacks per day. Consuming regular meals and healthy snacks can support your metabolism throughout the day.

  • Get Enough Sleep

    <strong>WHY IT WORKS:</strong> We get it, you're busy. But how often do you put sleep on your 'to do' list? Studies show that chronic lack of sleep can slow the metabolism, increase appetite and increase risks of obesity and weight gain, Barton says. Aim to get at least seven to eight hours of sleep a night so you wake up feeling refreshed, replenished and ready for the day ahead.

  • Exercise

    <strong>WHY IT WORKS:</strong> "Exercise is by far the safest and most effective way to boost your metabolism," Barton says. Exercise not only raises our metabolic rate, but as you exercise, it also keeps your resting energy expenditure high during the recovery period. Try at least 30 minutes of moderate to vigorous exercise a day, as well as two strength training sessions a week to keep your metabolism up.