It’s been well documented that our bodies experience hormonal and metabolic shifts throughout the day, with such factors as sleeping, eating, and exercising, also influencing these changes. Now, a group of researchers have published a study in the journal Obesity that suggests that getting the most of your carbs at dinner as opposed to spreading out those same evenly throughout the day might alter a person’s metabolism and hormonal patterns in such a way that it could help with weight loss.
The “Night-Carb Diet”
The researchers (from the Hebrew University of Jerusalem, Israel) found that consuming one’s carbohydrates primarily at night disrupts the usual daily pattern of a crucial appetite-governing hormone called leptin, which plays a key role in regulating the body’s energy intake and energy expenditure. It does this by sending messages to the brain that the body has had enough to eat, thus producing a feeling of satiety. In other words, leptin is a “weight-friendly” hormone.
The experiment involved a total of 78 male police officers, all with a body mass index (BMI) greater than 30 (within the obese range). It ran for six months and involved feeding each man a daily diet of 1,300 calories to 1,500 calories but with this difference: the men were randomized into two groups, with one group (the test group) getting their carbohydrates mostly at dinner, and the other group (the control group) receiving their carbs spaced out more evenly throughout the day. During any single day, all subjects ate the same number of calories.
The hypothesis was that because the “night-carb diet” 1) reduced insulin and 2) increased leptin levels, the men in the test group would experience greater feelings of fullness or satiety during the day and fewer hunger pangs, with the result that following the diet regimen would be less painful for them.
What the “Night-Carb Diet” Study Found
At the end of the six months, the test subjects who consumed their carbs mostly at night lost more weight (11.6 kg, or 25.5 lbs.) than did the men who spaced out their carbs throughout the day (9.06 kg, or 21.1 lbs.). The men in the test group also reported lower scores when surveyed about their feelings of hunger. And, physiologically, compared to the control group, the men who followed the “night-carb diet” scored considerably better with respect to their average daily insulin concentrations, fasting glucose levels, insulin resistance scores, lipid profiles, and inflammatory markers including C-reactive protein (CRP).
This six-month study revealed that a “Night-Carb Diet”
- Raised weight-friendly leptin levels for the next morning and throughout the day.
- Resulted in the body secreting just a single dose of insulin in the evening. Since insulin is a weight-promoting hormone that can lead to insulin resistance and the harmful effects of metabolic syndrome, less insulin production can often be beneficial when trying to lose weight.
Men in both the test group and the control group all experienced drops in leptin levels – this was to be expected, since the body naturally decreases leptin during periods of weight loss. But levels of the weight-friendly hormone fell by less among the “night-carb group” than in the controls.
The study authors suspect that these hormonal adaptations might explain the improvements in hunger scores and the many positive metabolic changes detected within the members of the test group. The scientists concluded, however, that additional research is needed to confirm and clarify the mechanisms that are altered with the “night-carb diet,” and how this diet is able to enhance satiety and improve weight loss and metabolism.
Balance, Balance, Balance
In spite of these fascinating results, I cannot recommend eating all your carbs at dinnertime, for several reasons. My whys and wherefores include your overall energy, your blood-glucose levels (especially among people with diabetes or hypoglycemia), as well as questions about when you’d eat fruits and vegetables in your diet.
Also, the types of carbs you ingest whether you choose high-fiber fruits, vegetables like healthful carrots, and grains or low-fiber “junk foods” and sweets make a big difference in your quality of life. (Even good, old, 100-percent, fruit juices don’t really provide much nutrition and don’t provide a feeling of satiety like you get by consuming the weight-friendly fiber in real fruits and veggies.)
Also, the “night-carb diet” might not be behind all the positive hormonal changes and greater weight loss seen in the men who followed that regimen. Their improvements might have been due at least in part to orexins or to the weight-friendly changes in metabolism and fullness sometimes seen when eating protein without carbs during the day.
And remember these general themes
Regardless of which “diet” you subscribe to, eating a healthy, balanced group of foods will give you a much bigger shot at success than signing on for another season of yo-yo dieting. Think of the foods you eat and your dietary habits as part of your lifestyle. Also practice intuitive or mindful eating, and listen to your body’s hunger signals and what it might be craving that is, satisfy your cravings with some combination of fresh fruits, vegetables, and whole grains.