For the last 50 years, North Americans have been raised with a deeply ingrained notion of the importance of three meals per day. But for how long has this meal pattern been around? As it turns out, not for very long — and basically since the beginning of the obesity epidemic.
The Romans ate a meal called dinner but it was their only meal of the day and it was around noon, according to a CBC food historian. They felt it was glutinous to eat more than one time per day. In the Middle Ages, dinner became a lavish affair, but was also towards the middle of the day. With no electricity, cooking or eating a meal after dark was not an option.
In the 17th Century, the spread of artificial lighting allowed dinner to be eaten later in the day. Meals began to be dictated by working hours and by the 18th Century most people were eating three meals per day. However, lunch at this time was still only a very quick snack to tide you over during a long day of factory work. There is some debate over how the word lunch originated — as it was rarely used until the 19th Century. One theory is that it stems from the word “nuncheon”, which translates into ‘a quick snack between meals that you can hold with your hands’.
It wasn’t until the 1950’s that most people pushed the dinner hour back into the evening. However, even at this time it was popular to maintain an early dinner hour on Sundays. From the 1950’s-1970’s the idea of a large dinner late in the evening was born. Not to mention refined and highly processed foods became widely available.
Isn’t it interesting then that in 1980’s the obesity epidemic was born. Now roughly 34% of North Americans are obese. Although this is the fault of many societal norms, eating a late dinner is now understood to disrupt the human circadian rhythm, setting the stage for obesity as a chronobiological disease.
Research shows that consuming late meals influences circadian rhythms in humans. Plasma glucose, as well as adipose PER2 markers (responsible for lipid metabolism), are both delayed by late meal timing. Furthermore, earlier studies show that if the exact same meal is consumed in the morning and evening — there is a 25–50% greater insulin response at night. This again suggests that eating a larger meal in the morning is beneficial for weight management — especially if consuming carbohydrates.
A recent systematic literature review revealed that meal timing is a relevant factor in obesity, with food intake late at night being linked to weight gain, hyperglycaemia, and type-2 diabetes. The study also demonstrated that corrective changes in meal timing can positively influence weight loss therapies independent from total caloric intake, energy expenditure, and macronutrient distribution.
Eating the largest meal of the day in the morning or afternoon is becoming recognized as optimal for human health. Humans unfortunately fell into the societal norm of having a large dinner after a long work day, and we are just beginning to realize the detrimental effects it has on chronic disease risk. Is this the only factor contributing to rising obesity — of course not. However, connecting this link and working to adjust societal norms around meal timing would definitely be a positive step forward.
Originally published at medium.com