The researchers found that the internal circadian system regulated hunger, with participants feeling the least hungry in the morning (8 a.m.) and most hungry in the evening (8 p.m.).
“Our study suggests that because of the internal circadian regulation of appetite, we have a natural tendency to skip breakfast in favor of larger meals in the evening. This pattern of food intake across the day is exactly what Sumo wrestlers do to gain weight.” said Steven Shea. “So, it seems likely that the internal circadian system helps with efficient food storage. While this may have been valuable throughout evolution, nowadays it is likely to contribute to the national epidemic of obesity.“
Here's another study:
Circadian clock linked to obesity, diabetes, heart disease
This is a study on mice, which have similar molecular structures to ours. Their cycles are a mirror image of ours--they are active at night, while we are inactive at night.
"Mouse tissues are relatively resistant to insulin [convert food to fat] during the inactive/fasting phase [our night time cycle].
"Whereas they become more sensitive to insulin (therefore better able to transfer glucose out of the blood [and NOT convert it to fat]) during the high activity/feeding phase [our day time ] of their 24-hour cycle.
"As a result, glucose is converted primarily into fat during the inactive phase and used for energy and to other tissue building during the high activity phase."
“That is why it is good to fast every day…not eat anything between dinner and breakfast,” said Johnson [one of the researchers].The take away? I'm wired to eat at night. I have to fight evolution to eat breakfast early and not eat the house down after 8 pm. Of course we have practical, real life experience of the results of eating at night, although I have read health/fitness articles in the past that say it doesn't matter when you eat--a calorie is a calorie is a calorie.... calories in/calories out. But that's simply not true, as evidenced by our experience and now by scientific research. I guess it's helpful to understand the WHY's of my behavior. But it's still a fight to change. Thanks a bunch, evolution.