This is the weird reason you can’t lose weight, according to science

Fortunately (and unfortunately) weight loss is a science. And as is the case with any science, there are many variables to consider when trying to obtain optimal results. 

Recent literature on the subject has shown time and time again that scheduling goes hand in hand with diet and calorie restriction, i.e when we eat is just as important as what and how much we eat in regards to our overall health.

A new crossover clinical study, published in the Journal of Clinical Endocrinology & Metabolism adds to this development by concluding people who eat a late dinner not only burn less fat overnight, but they also have higher blood sugar levels compared to those who habitually eat their dinner earlier in the evening.

“Consuming calories later in the day is associated with obesity and metabolic syndrome,” the researchers wrote in the new paper. “We hypothesized that eating a late dinner alters substrate metabolism during sleep in a manner that promotes obesity.  These metabolic changes were most pronounced in habitual earlier sleepers determined by actigraphy monitoring.”

Metabolic Effects of Late Dinner in Healthy Volunteers 

To support their hypothesis, the authors recruited 20 healthy volunteers-half of which were men the other half of which were women.

Each was instructed to eat a macronutrient inspired dinner composed of the same foods (35% daily kcal, 50% carbohydrate, and 35% fat)) and portions at either 6 p.m. or 10 p.m before going to bed at 11 pm. 

By employing body fat scans, activity trackers, hourly blood samples, and non-radioactive tracers,  the researchers were able to measure both blood sugar levels and the speed at which the participants burned fat.

The analysis determined late dinner eaters reduced their fat-burning duration by 10% and peak blood sugar levels were nearly  20% higher among this group compared to the early dinner eaters. 

As far as the real-world application is concerned: the earlier the bedtime, the starker the results.

Late dinner seemed to induce nocturnal glucose intolerance, and decrease fatty acid oxidation and mobilization in earlier sleepers. 

Physiologically speaking, it’s not that calories count later in the evening. It’s that our bodies respond to foods differently depending on time and our chronotypes. This miscommunication causes us to gain less from nutrients while making the most out of fatty foods.  

Moreover, most of us are more inclined to choose unhealthy food options at nighttime compared to the day. 

“This study sheds new light on how eating a late dinner worsens glucose tolerance and reduces the amount of fat burned. The effect of late eating varies greatly between people and depends on their usual bedtime,” explained researcher Dr. Jonathan Jun, in a media release. “This shows that some people might be more vulnerable to late eating than others. If the metabolic effects we observed with a single meal keep occurring chronically, then late eating could lead to consequences such as diabetes or obesity.”

CW Headley is a reporter for the Ladders and can be reached at