Here’s a novel reason why it can be hard for some people to shed pounds: Their burn rate is less after eating a meal. A study presented at the virtual American Diabetes Association Scientific Sessions found that people with higher body mass index levels produced less body heat after an oral glucose tolerance test than those with lower BMI levels.

Since post-feeding thermogenesis (involved in digesting and metabolizing food) contributes to total daily calorie burn, lower rates in people who are overweight could be another reason why weight loss can be oh-so-challenging.

See also: Fast and Furious Fat Burning