If you like to pile up your plate, you’re much better off doing it at breakfast.
According to a Tel Aviv University study, human metabolism is significantly impacted by our body clock — the circadian rhythm that manages our body’s biological processes over each 24-hour cycle.
Eating a big breakfast jumpstarts metabolic processes and keeps them high all day. And according to the study, by Daniela Jakubowicz of TAU’s Sackler Faculty of Medicine and the Diabetes Unit at Holon’s Wolfson Medical Center, those who eat their largest daily meal at breakfast are far more likely to lose weight and waistline circumference than those who eat a large dinner.
To determine the impact of timing on weight loss and health, Jakubowicz and her fellow researchers, Julio Wainstein of TAU and Maayan Barnea and Oren Froy of Hebrew University, conducted a study in which 93 obese women were randomly assigned to two groups, each of which was given a diet of moderate-carbohydrate and moderate-fat foods with a daily total of 1,400 calories. The results of the study were published in a recent edition of the medical journal Obesity.
The difference between the groups was in their “calorie timing”: The first group ate 700 of their allotted calories at breakfast, 500 at lunch, and 200 at dinner, while the second group ate a 200-calorie breakfast, a 500-calorie lunch, and 700-calorie dinner. As a further control, the 700-calorie breakfast or dinner for each group included the same foods.
While members of both groups lost weight as expected, as all participants had significantly reduced their calorie consumption, the 12-week study showed that when they ate those calories had a big impact on weight loss. Those who ate the big breakfast lost an average of 17.8 pounds each and three inches off their waistline, while those in the big dinner group lost only 7.3 pounds and 1.4 inches off their waistline.
In addition, said Jakubowicz, those in the big-breakfast group were found to have significantly lower levels of the hunger-regulating hormone ghrelin, an indication that they were more satiated and had less desire for snacking later in the day than their counterparts in the big-dinner group.
The big breakfast group also showed a more significant decrease in insulin, glucose, and triglyceride levels than those in the big dinner group. More importantly, they did not experience the high spikes in blood glucose levels that typically occur after a meal. Peaks in blood sugar levels are considered even more harmful than sustained high blood glucose levels, causing high blood pressure and greater strain on the heart and eventually leading to strokes or heart attacks, according to medical researchers.
The best part of Jakubowicz’s findings: Breakfast doesn’t have to be just a bowl of oatmeal or granola. Participants in the study were given some “high risk” items with their big breakfasts, including cookies or cake, and they still experienced the benefits of increased metabolism throughout the day. They also showed significantly lower levels of insulin, glucose, and triglycerides, translating into a lower risk of cardiovascular disease, diabetes, hypertension, and high cholesterol, the study showed.
Jakubowicz has been studying calorie timing for several years. In a 2012 study published in the journal Steroids, Jakubowicz and her team found that people trying to lose weight were better off not only eating a big breakfast, but also indulging in some “forbidden foods” they were probably trying to avoid, like sweets. Over the course of a 32-week study, participants who added dessert to their breakfast — cookies, cake, or chocolate — lost an average of 40 pounds more than a group that avoided such foods. They also kept off the pounds longer.
In that study, 193 clinically obese, non-diabetic adults were randomly assigned to one of two diet groups with identical caloric intake — with the men consuming 1,600 calories per day and the women 1,400. The first group was given a low carbohydrate diet including a small 300-calorie breakfast, and the second was given a 600-calorie breakfast high in protein and carbohydrates, always including a dessert item (e.g., chocolate).
Halfway through the study, participants in both groups had lost an average of 33 pounds per person, again consistent with the far lower calorie intake the diet provided. But in the second half of the study, results differed drastically. The participants in the low-carbohydrate group, unable to withstand temptation any longer, began cheating on their diet and regained an average of 22 pounds. Participants in the group with a larger breakfast, however, lost another 15 pounds apiece. At the end of the 32 weeks, those who had consumed a 600-calorie breakfast had lost an average of 40 pounds more per person than their peers.
Thirty-two weeks is a long time to go without goodies, it seems, and according to Jakubowicz, the results of the the 2012 study show that denying oneself won’t work in the long run.
“The participants in the low carbohydrate diet group had less satisfaction, and felt that they were not full,” she said, noting that their cravings for sugars and carbohydrates were more intense and eventually caused them to cheat on the diet plan. “But the group that consumed a bigger breakfast, including dessert, experienced few if any cravings for these foods later in the day.”
Jakubowicz’s study corroborates findings from another study conducted over the past two years led by Dr. Craig Johnston, assistant professor of pediatrics at Baylor College of Medicine. In that study, 70 teenagers were offered a cereal breakfast each morning, received nutrition education once per week and exercised four times per week. They were also provided a nutritious snack before leaving school.
After six months, the group of adolescents had significantly lowered their body mass index, a result that persisted even two years later, with the teens who had eaten breakfast consistently maintaining lower BMI than a test group that had been given a manual on how to lose weight.
The two studies are part of a growing body of evidence that proves the old adage that “breakfast is the most important meal of the day” — even if it includes chocolate cake for dessert.