Do you skip breakfast? Skipping breakfast to burn fat? What Skipping Breakfast Does to Your Body?

What impact does a morning fast have on your body's metabolism?
( Helena Lopes)

Do you skip breakfast?
Whether by accident or design, many of us miss our morning meal.
"There's a lot of observational evidence of breakfast consumption. We know that people who regularly consume breakfast are typically less heavy than other people," said Javier Gonzalez, associate professor of human physiology at the University of Bath.
"But they are also healthier in many other ways, so they are more likely to be physically active and drink less alcohol and so on."
What wasn't clear was whether those differences were because of something about the character of those people who ate breakfast — that they led healthier lives in general — or if it was directly caused by breakfast consumption.
To answer that question, Dr Gonzalez and his colleagues designed a trial that split 49 participants into two groups. One group skipped breakfast every day for six weeks — meaning they didn't eat any calories until midday.
The other group were asked to eat at least 350 calories within two hours of waking, and at least 700 calories by 11:00am. Both groups contained lean and obese participants.
In research published in the Journal of Physiology, they found that in the group of participants that fasted and were not overweight, skipping breakfast increased the activity of the genes involved in fat metabolism.
That suggests that their fat cells were switching to fat as a fuel — that is, they were burning more fat by skipping breakfast.
For those who ate breakfast, the activity of those genes decreased.
While it may then sound like skipping breakfast is the best option for those who want to lose weight, there are a couple of caveats. The researchers found that whether or not a lean person ate breakfast, their total energy balance for the day was about the same.
The authors suggest while skipping breakfast may make you burn fat, it also makes you less active during the day.
"What is clear is that by regularly consuming breakfast people tend to be more physically active, and that's not going to the gym, it's your spontaneous activity that you are not aware of," Dr Gonzalez said.
Participants in the study self-selected their breakfast, but what they chose was monitored by the researchers. For the most part, they chose carbohydrate-heavy food — things like toast and cereal, rather than bacon and eggs.
Response differs for obese people
For obese people in the study, that same variation of the genes regulating fat cells was not observed. If anything, some of those genes became slightly less active.
"The obese group were more resistant to the intervention of breakfast versus fasting. They seemed to respond similarly regardless of meal timing," Dr Gonzalez said.
Another important difference between the fat cells of lean and obese people was their response to insulin.
In the lean people, eating breakfast decreased the activity of genes involved in insulin resistance.
That was a positive effect which meant they pulled more sugar out of their blood — a mechanism potentially protective against diabetes.
For obese people, eating breakfast didn't improve their ability to take up sugar in their fat cells.
The researchers say this could be a mechanism to prevent the person from putting on more weight.
"This insulin resistance in the fat cells of obese people, it seemed to be perfectly proportional with the amount of total body fat they had."
"It does suggest that because glucose is important in the process of storing fats it seems like it's a down-regulation, their fat cells are turning off their ability to take up glucose and store fat."
So should you fast?
What's clear from this particular piece of research is there's no one-size-fits-all. Given your total energy balance tends to end up around the same whether or not you eat breakfast, Dr Gonzalez said either method may be suitable for those who may want to lose weight.
But he said those who fast should be aware that their physical activity levels might fall, and that breakfast may be beneficial in other ways to a person's overall health — not just weight.
"If you'd like to try some form of intermittent fasting, then just be aware that your physical activity levels might drop a little bit," Dr Gonzalez said.
"Of course you can counteract that, by being aware of this you can perhaps time your physical activity or your gym sessions.
"Furthermore, this evidence suggests that we should perhaps consider altering the current guidelines for breakfast consumption and these guidelines may need to consider the weight status of the individual. We certainly need more research to understand what is the optimal type of breakfast for body weight and health."
Here's What Skipping Breakfast Does to Your Body
It’s a hotly contested question in the nutrition world: is breakfast really the most important meal of the day? Experts say that people who eat breakfast are less likely to overeat the rest of the day, but recent studies have found no difference in weight between those who skip their morning meal and those who don’t. In the meantime, skipping meals has become an increasingly popular part of modern life.
Breakfast-eaters tend to have lower rates of heart disease, high blood pressure and high cholesterol, the American Heart Association reported earlier this year, but the group says the science isn’t strong enough to suggest that people who don’t normally eat breakfast should start. On the other hand, some research has even suggested that fasting for longer overnight periods (eating an early dinner, for example) could actually help people lose weight.
Now, a small new study in the American Journal of Clinical Nutrition sheds some light on what really happens in the body when people skip breakfast on a regular basis. People burn more calories on days they skip breakfast, but that the habit may increase dangerous inflammation.
Researchers from the University of Hohenheim in Germany tested 17 healthy adults on three separate days: once when they skipped breakfast, once when they had three regular meals and once when they skipped dinner. Despite the change in scheduling, the calorie content and breakdown of carbohydrates, fat and protein were the same on all three days. (On days with a skipped meal, the other two meals had extra calories to make up for it.) Each day, blood samples were collected frequently from 7 a.m. until 9 p.m. to measure hormone levels, glucose and insulin concentrations, and immune cell activity.
They found that people burned more calories over a 24-hour period when they extended their overnight fast by skipping either lunch (41 more calories) or dinner (91 more calories), compared with the three-meals-a-day schedule. These findings are in line with other studies on time-restricted eating.
They found no difference in 24-hour glucose levels, insulin secretion or total physical activity between the three days. But glucose concentrations and markers of inflammation and insulin resistance were higher after lunch on breakfast-skipping days.
People also oxidized more fat, meaning their bodies broke down more of their stored fat reserves, on days when they skipped breakfast. That may sound like a good thing, but the researchers say it could have a downside. It suggests an impairment in metabolic flexibility, the body’s ability to switch between burning fat and carbohydrates—which “may in the long term lead to low-grade inflammation and impaired glucose homeostasis,” they wrote.
The researchers concluded that because chronic inflammation is known to affect insulin sensitivity, skipping breakfast could contribute to “metabolic impairment,” which could potentially raise the risk for obesity and type 2 diabetes.
Courtney Peterson, assistant professor of nutrition sciences at the University of Alabama Birmingham, says that more research is needed in order to know the bottom line on breakfast. It’s too early to know whether skipping breakfast has a meaningful effect on inflammation levels, she says, and “the authors’ data does not support the idea that breakfast skipping is bad for health.” Peterson, who was not involved in the new research, studies time-restricted eating. (She led the 2016 study mentioned above, which found that eating an early dinner can boost calorie burn.)
Because the researchers only measured inflammation levels after lunch, she says, “it’s possible that skipping breakfast increases inflammation at lunchtime but decreases it other times of the day.” And because the study was only a few days long, it can’t say whether skipping breakfast regularly would affect health or metabolism.
The study also suggests that skipping breakfast or dinner might help people lose weight, since they burned more calories on those days. Yet she says that the elevated levels of inflammation noted after lunch “could be a problem,” and adds that the finding warrants further research. Skipping meals and other types of intermittent fasting may not be realistic for most people, Peterson says—and it does have the potential to backfire if it triggers unhealthy snacking or overeating later on.
You may even want to rethink which meal you’re sacrificing. Because calorie burn in this study was greater when skipping dinner compared with skipping breakfast, Peterson says “it might be better for weight loss to skip dinner than to skip breakfast.”
This fits with what’s already known about humans’ circadian clock, she adds: “Your metabolism and blood sugar control are better in the morning than they are in the evening and at night, so it makes sense to eat more food earlier in the day.”

No comments