Does the Timing of Your Meals Really Matter for Weight and Fat Loss?

A number of preclinical and some clinical studies support the effectiveness of time-restricted eating (TRE) in weight loss and management of metabolic disturbances associated with obesity. However, human studies have not always shown consistent results. A recent study published in Nature Medicine observed whether limiting food intake to an 8-hour window each day could help people with overweight or obesity lose weight and improve their health, and if the timing of this eating window (early in the day, late in the day, or self-selected) made a difference.

Researchers in Spain conducted a 12-week randomized controlled trial involving 197 adults who were overweight or obese. Participants were divided into four groups: a usual care group (UC) who received education about the Mediterranean diet, an early time-restricted eating (TRE) group with an 8-hour eating window ending by 6pm, a late TRE group with an 8-hour eating window starting around 2pm, and a self-selected TRE group who chose their own 8-hour eating window. All TRE groups also received the same education about the Mediterranean diet as the usual care group.

“…all three TRE groups (early, late, and self-selected) experienced significantly greater body weight loss compared to the usual care group.”

The study aimed to see how these different eating schedules affected visceral adipose tissue (VAT), a type of abdominal fat located around internal organs that is an important risk factor for cardiometabolic morbidity and mortality. The researchers found that combining time-restricted eating with a Mediterranean diet did not significantly reduce visceral adipose tissue (VAT) compared to following a Mediterranean diet alone, regardless of whether the eating window was in the early or late part of the day or chosen by the participant. However, all three TRE groups (early, late, and self-selected) experienced significantly greater body weight loss compared to the usual care group. The average weight loss in the TRE groups was around 2.4 to 3.1 kg more than in the usual care group.

• The early TRE group showed a greater reduction in subcutaneous adipose tissue (SAT), the fat just under the skin, compared to the usual care group.
• The early TRE group also had greater decreases in fasting glucose and nighttime glucose levels compared to the usual care, late TRE, and self-selected TRE groups.
• There were no significant differences in VAT reduction, body weight loss, or changes in other cardiometabolic risk factors (like blood pressure and cholesterol) among the three different TRE groups (early, late, and self-selected).
• Adherence to the TRE schedules was high across all three TRE groups, suggesting it is a realistic dietary approach for those looking to manage and maintain weight loss.

“The timing of this 8-hour window may not be as critical for overall weight loss as simply restricting the eating window itself.”

This study suggests that while following a Mediterranean diet is beneficial, adding an 8-hour time-restricted eating window can lead to additional weight loss for individuals who are overweight or obese. Notably, the timing of this 8-hour window may not be as critical for overall weight loss as simply restricting the eating window itself. However, an earlier eating window might offer some extra benefits for blood sugar levels and the reduction of fat under the skin.

“Incorporating an 8-hour eating schedule along with a healthy diet of fruits, vegetables and whole grains while avoiding ultra-processed foods can be an effective strategy for managing and maintaining weight loss for individuals struggling with obesity.”

The researchers concluded that time-restricted eating, regardless of the specific timing, can be a safe and tolerable dietary strategy for individuals struggling with obesity. Combining TRE with a healthy diet, such as the Mediterranean diet can lead to weight loss, however it doesn’t appear to offer an extra advantage in reducing harmful abdominal fat (VAT) compared to following the Mediterranean diet alone.

Overall, incorporating an 8-hour eating schedule along with a healthy diet of fruits, vegetables and whole grains while avoiding ultra-processed foods can be an effective strategy for managing and maintaining weight loss for individuals struggling with obesity.