Internal Circadian Clock and Weight Gain
In a 2013 study published in Obesity, researchers from the Division of Sleep Medicine with Brigham and Women’s Hospital in Boston, MA evaluated the relationship between appetite and our internal circadian sleep clock. What the researchers found was surprising.
Twenty healthy non-obese adults were studied throughout a 13-day period. Standard laboratory protocol procedures were followed to normalize total calories ingested and calories expended. Participants rated their appetite and food preferences throughout the study. The study found that the desire for food was greatest at 7:50 pm and at it’s lowest at 7:50 am. They also found an increased appetite for sweet, salty and starchy foods, fruits and meats/poultry, and food overall in the evenings. The increase in appetite in the evening was evaluated to be in the 14-25% range! Also noteworthy was a lack of desire among study participants to eat vegetables; suggesting that the circadian system regulates the desire to eat high calorie foods.
The circadian rhythm and hunger peaks in the evening may have provided our ancestors an evolutionary advantage in times of food shortages because eating the largest meal in the evening, prior to sleep, leads to increased weigh gain. Unfortunately, now with nearly unlimited access to high fat/calorie foods and an increased desire to eat sweet, starchy foods, especially in the evenings, unwanted weight gain occurs.
What do we do with this information? Know that our desire to eat high starchy, high calories foods may be a natural occurrence and that we can mitigate weight gain though several steps.
- Eat your last meal of the day at least 3 hours prior to sleep. If this is not possible eat a low calorie “dinner” high in vegetables and low in fat. Reduce or eliminate snacking after dinner and before bedtime.
- Train yourself to eat within 60 minutes of waking and continue to eat throughout the day in 3 hour intervals.
- Determine what your total calorie requirements are and spread them out equally through the day eating every 3 hours.
- Make nutrient dense food decisions. Focus on fruits, vegetables and lean sources of protein as the primary source of calories in your diet.