You already know a busy lifestyle can mean an unhealthy diet. However, it seems, even if you're eating the right things, an irregular intake can also play a disruptive role in health. A new study at Ohio State University (OSU) suggests that skipping meals can upset the body's natural order and contribute to an increase in the belly fat associated with diabetes.
The study, which was published online in the Journal of Nutritional Biochemistry, compared the results from two groups of mice. The first group — the "control" group — was allowed to eat as much as they liked and followed normal feeding patterns. The diet of the second group was restricted, meaning that, effectively, they got to eat only once a day. For three days, these mice received half the daily calories of the control mice. Food was gradually added so that, by day six, all mice received the same amount of food. As you might expect, at first, the mice on the restricted diet lost weight compared to control group. They also, naturally, regained weight as their intake was increased.
Importantly, even after fasting, the mice following the restricted diet gained more fat around their middles — that which is comparable to human belly fat — than the mice that ate regularly. An excess of this kind of fat is associated with insulin resistance and risk for type 2 diabetes and heart disease. It was discovered that the mice that ate all of their food as a single meal and fasted the rest of the day developed insulin resistance.
The explanation can be seen by looking at the body's means of controlling blood sugar. When you eat, carbohydrates are broken down into their simplest form — glucose — and released into the blood where they can be used for energy. The body needs to keep the level of blood sugar within a certain narrow frame so it turns any excess glucose into long chains called glycogen, which are stored in the liver and muscle. When you get hungry, glucose levels drop and the body compensates by making and releasing more from the stored glycogen.
One of the key players in this mechanism is insulin. Insulin has a number of important roles Firstly, it instructs the body when to store glucose and, secondly, it tells it to stop producing more. Insulin also helps muscle, fat, and liver cells absorb glucose from the bloodstream, lowering overall blood sugar levels. If, however, for some reason the liver doesn’t respond to insulin signals telling it to stop producing glucose, extra sugar in the blood is stored as fat.
In the study, the mice that had been on restricted diets developed gorging behavior that persisted throughout the study, meaning they finished their day’s worth of food in about four hours and then ended up fasting for the next 20 hours. “With the mice, this is basically bingeing and then fasting,” says Martha Belury, professor of human nutrition at OSU and senior author of the study. This, she suggests, is comparable to the eating patterns of some people with busy lives. “People don’t necessarily do that over a 24-hour period, but some people do eat just one large meal a day.”
Glucose levels tend to spike in the morning. The liver releases glucose when insulin levels are low but that production stops after a meal, when the pancreas releases insulin to remove sugar from the blood. Belury's team found that glucose lingered in the blood of mice that gorged and fasted — meaning the liver wasn’t getting the insulin message. “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,” Belury said. “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.”
This pattern of gorging and fasting affects the natural metabolic process and the researchers linked it to a spike and then severe drop in insulin production. When the two groups were compared, the mice whose diets were disrupted experienced an increase in the storage of fatty tissue, especially in the abdominal area. Insulin resistance is a known factor for gaining abdominal fat known as white adipose tissue and an increase in this was seen in the diet-restricted mice. "Even though the gorging and fasting mice had about the same body weights as control mice, their adipose deposits were heavier," Belury says. "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."
The long-term problems, it seems, far outweigh the short term gains. “This does support the notion that small meals throughout the day can be helpful for weight loss, though that may not be practical for many people,” she says. “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.”