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The Body Adapts To Occasional Short-Term Overeating

It’s known that overeating impairs blood sugar control and insulin levels. Now, a new study from Australia suggests that the duration of overeating can affect how the body adapts glucose and insulin processing when calorie intake increases.

Obesity and Type 2 diabetes have increased significantly worldwide within the past 30 years. Lifestyle factors such as overindulging in high-calorie foods play a large role in the development of these two serious health conditions.

“The study was conducted to examine which tissues are impaired first in response to overeating,” Dr. Glenn Wadley, study author and associate professor at Deakin University, tells dLife. “We initially hypothesized, based on earlier studies, that the liver would be impaired first by short-term overeating and then skeletal muscle — which soaks up much of the glucose following a meal — would be impaired much later with chronic overeating.”

However, Wadley explains his team didn’t find this.

“The study found that the body copes with short periods of overeating and makes adjustments by shifting metabolism towards using more carbohydrates,” he says. “But we aren’t advocating that regular binge eating is okay.”

His team speculates that from an evolutionary perspective, the body is okay occasionally with a few days of feasting, probably because it’s preparing us for the next famine.

“The issue nowadays is food is always plentiful – so from a health perspective, short-term overeating is really best confined to infrequent special occasions, like during festivals and holidays,” Wadley explains.

How Was The Study Conducted?

Researchers studied a small group of healthy, lean men with an average age of 22. Volunteers participated in a short-term trial consisting of five days –indicative of humans overeating during festivals and holidays– and a long-term model of chronic overeating lasting 28 days.

The nutritional composition of the volunteers’ diet was representative of a typical Australian diet (55 percent carbohydrates, 35 percent fat and 15 percent protein).

The “overfeeding” portion of the diet included high-calorie snacks such as chocolate, meal replacement drinks and potato chips to add approximately 1,000 more calories to the men’s normal food consumption each day.

The research team measured the volunteers’ weight, fat mass, blood sugar, and insulin levels before the trial began and again after five and 28 days.

Although the amount of visceral fat that surrounds internal organs increased substantially, short-term overeating did not have a significant effect on the men’s weight or fat mass.

In addition, fasting levels of blood sugar and C-peptide–an amino acid the body releases in response to increased production of insulin–did not change.

This finding was surprising because fasting levels of endogenous glucose–new glucose the body produces in addition to what it has already stored for future use–increased during the short-term trial.

Chronic overeating increased the amount of total body fat and visceral fat as well as post-meal blood sugar and C-peptide levels.

However, it did not alter fasting blood sugar levels, endogenous glucose production or the rate of glucose removal from the body (glucose disposal).

This may be because the nutrient profile in the long-term trial was consistent with a typical diet and dietary fat percentages did not increase.

Long-term overindulgence in fatty foods, instead of more nutritionally balanced foods, may be an important factor that causes rapid changes in blood sugar control.

“Our participants were young and within a healthy weight range,” Wadley says,  “it’s possible their bodies are better able to cope with the oversupply of food and it would be interesting to follow the study up in an older or overweight cohort.”

Also, whether the findings could be relevant for females, Wadley says it’s quite likely they would see similar overall results in since excess food intake that leads to higher body weight also impairs the ability to utilize carbohydrates.

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