Resolutions, resolutions. After a month (or two) of indulging in holiday treats, weight loss is the hot topic of January. We all know a combination of healthy eating and exercise is the key to dropping unwanted pounds, but research now suggests there could be more to weight loss than counting calories and steps. A recent study in the journal Cell Metabolism suggests limiting allowed hours for eating, regardless of calories and fat, could help keep you slimmer and healthier.

To determine the effect that time-restricted eating – that is, eating only within a specific time frame each day – has on weight and other health parameters, researchers evaluated mice under various conditions of diet. Mice were fed a normal, high-fat, or high-sugar diet, and were given access to food for 9, 12, 15, or 24 hours of the day. Different combinations of diet and time were tested.

Not surprisingly, mice on a high-fat diet gained weight. However, mice given access to food only 9 hours per day showed weight gain of 26%, while mice with 24-hour access gained 65%, even though calories were equivalent. In a different test on already obese mice given access to food at all hours of the day, switching to a 9-hour restricted diet resulted in 12% weight loss. Comparatively, obese mice who stuck with the freewill diet gained an additional 10.6%, even though calories between the groups stayed the same.

Researchers also tested modeling how most people typically eat – strict during the week and maybe not so strict on the weekends. Mice alternated between five days of 9-hour restricted eating (weekdays) and two days of all hours dining (weekends). These mice gained only 29% body weight compared with a 61% gain in mice that stayed in “weekend mode” seven days a week.

Investigators then went beyond weight and looked at other health parameters associated with obesity. Mice on the weekday/weekend diet pattern had 48% less body fat than all-hours eaters, and mice committed to the 9-hour restriction had 57% less fat. Restricted mice were also absent of inflammation in fat tissue and had 70% fewer triglycerides, lower cholesterol, and improved insulin resistance compared with all-hours eaters. Restriction also proved to help with fitness and endurance on treadmill runs.

What does this mean for humans? Don’t indulge in the midday cake just yet. Managing calories is still an important element of successful weight maintenance, but perhaps this is another reason to forgo that midnight snack. In mice, restricting eating to only 9 hours per day was effective in counteracting some of the negative effects of obesity. Results also indicated time restriction could help prevent weight gain during indulgent dining (ahem, next holiday season). And lucky for us, the weekday plan was still effective with a little wiggle room on the weekends. Fill half your plate with fruits and vegetables, swap your afternoon cookie for a banana, and try to keep a regular eating pattern and time frame if your schedule allows. Time restriction isn’t the magic key for weight loss, but it could be a step in the right direction.

Published January 1, 2015