A new study of mice suggests skipping meals may disrupt metabolism in a way that leads to extra fat accumulating around
the middle and signs of prediabetes.
The researchers suggest skipping meals to save calories could be counterproductive as it results in larger fluctuations of
insulin and glucose that can lead to more fat gain instead of fat loss.
Writing in the The Journal of Nutritional Biochemistry, the researchers, including members from Ohio State University
in Columbus, describe how they compared mice allowed to nibble their food throughout the day with mice that ate their food in one
session and then fasted for the rest of the time.
They found that the mice that gorged all their day’s food in one session and fasted in between developed
insulin resistance in their livers – an indicator of prediabetes – and more fat in their abdomens.
When the liver becomes less sensitive to insulin, it keeps producing glucose when it is not needed, so the blood ends up with
too much sugar and the excess is stored as fat.
For the experiment, the researchers initiated gorging behavior in the mice. They had two groups of mice: the control and the
intervention group. Controls were given their full daily food ration once a day – which they nibbled all day.
At first, the intervention group was given a restricted calorie diet. For 3 days their daily food ration had half the calories
of that given to the controls. This initiated gorging behavior – they ate all their food in one session and then fasted.
Then, over another 3 days, the intervention (now gorging) mice were gradually given more and more calories until their rations
were the same as the controls. But they continued with their gorging and fasting pattern – they did not go back to nibbling like
the controls. They ate all their food in a period of 4 hours and then fasted for 20 hours.
Gorging mice had same weight but more belly fat than mice that nibbled all day
Over the period of the experiment the researchers measured various metabolism indicators in the mice.
They found that at first, as they were on calorie restriction, the intervention mice lost weight compared with the controls. And
as they were given more and more calories, their weight returned to match the controls.
But around their middles – where humans carry their belly fat – by the end of the experiment, the gorging mice had
accumulated heavier amounts of abdominal fat.
Carrying excess belly fat is linked to insulin resistance and higher risk of developing type 2 diabetes and heart disease.
Senior author Martha Belury, professor of human nutrition at Ohio, says their findings support the idea that eating small
meals throughout the day can help lose weight, although that may not be practical for everyone. However, she also notes:
“But you definitely don’t want to skip meals to save calories because it sets your body up for larger fluctuations in
insulin and glucose and could be setting you up for more fat gain instead of fat loss.”
She says by the end of the experiment, the intervention mice were basically bingeing and fasting. “People don’t necessarily do
that over a 24-hour period, but some people do eat just one large meal a day,” she notes.
Gorging and fasting also led to prediabetes
The team compared the metabolic measures in the intervention mice with the nibbling mice. When the intervention mice gorged
then fasted, they had higher levels of inflammation.
This was also accompanied by higher activity in genes that promote storage of fatty molecules and plumper fat cells –
especially in the abdomen. The researchers attribute these changes to spikes and then severe drops in insulin.
The researchers also looked at what was happening in the liver. When insulin levels fall – for instance, when we are asleep –
the liver pumps glucose into the blood to feed the brain. When we eat, the pancreas pumps out insulin to move glucose from the
blood to the cells that need it for energy. This rise in insulin instructs the liver to stop pumping glucose.
The team found glucose was lingering in the blood of the intervention mice – suggesting the liver was not receiving the
insulin message that tells it to stop producing glucose. Prof. Belury explains how this links to diabetes:
“Under conditions when the liver is not stimulated by insulin, increased glucose output from the liver means the
liver isn’t responding to signals telling it to shut down glucose production. These mice don’t have type 2 diabetes yet, but
they’re not responding to insulin anymore and that state of insulin resistance is referred to as prediabetes.”
Insulin resistance could also be why the intervention mice gained abdominal fat – known as white adipose tissue – that stores
energy. Even though they had the same body weight as the controls, their adipose tissue was heavier.
“If you’re pumping out more sugar into the blood, adipose is happy to pick up glucose and store it. That makes for a happy fat
cell – but it’s not the one you want to have. We want to shrink these cells to reduce fat tissue,” Prof. Belury adds.
Funds from the Carol S. Kennedy endowment, the Ohio Agricultural Research and Development Center and the National Institutes
of Health helped finance the study.
Meanwhile, Medical News Today recently learned of a study published in JAMA that estimates metabolic syndrome affects more than a third of American adults, and almost half of those aged 60
and over, a statistic that the researchers note should be a cause for concern – especially as the US population is aging.