We at The Huffington Post have no problem calling breakfast the most important meal of the day, and generally, experts don’t either. Long term studies link skipping breakfast to a higher risk of obesity, coronary heart disease and type 2 diabetes, while eating breakfast is linked to a bunch of other benefits like a higher I.Q.
But these studies, long-term though they may be, only establish a correlational relationship between breakfast and health outcomes. In other words, they don’t demonstrate that eating or not eating breakfast actually causes these diseases and conditions. Instead, they simply show if a person is more or less likely to be at risk of something based on their breakfast habits.
So what kind of research can show a cause-and-effect relationship between breakfast and health? Randomized controlled trials, in which one group of participants is told to skip breakfast, while a control group eats breakfast as normal (or vice versa). These results are generally considered stronger evidence than the studies that only reveal a correlation. Breakfast researchers who conduct these kinds of trials are a lot less convinced of the meal's supposed ability to help us lose weight and avoid chronic disease.
Here are a few recent RCTs and their findings about how breakfast affects health.
1. Eating breakfast doesn’t appear to have any effect on the ability to lose weight.
Researchers from University of Alabama at Birmingham randomized 300 healthy but overweight or obese adults to one of three groups: people who would eat breakfast, people who would skip breakfast and people who would continue however they normally did. Researchers found that after four months, both breakfast eaters and skippers were able to lose weight, and it made no significant difference whether they ate in the morning or not. One caveat about the findings, published in 2014, was that researchers only measured weight and not body composition, which could have given us a clue about the potential metabolic difference between breakfast eaters and skippers.
2. People who eat breakfast are more physically active and have more stable blood sugar levels.
Researchers from Bath assigned 33 normal-weight people to either eat breakfast (about 700 calories by 11 a.m.) or skip breakfast (which meant no calories until noon). After six weeks, there was no difference between the two groups in terms of cardiovascular health or resting metabolism. But breakfast eaters were more physically active overall, and they had more stable blood sugar levels in the afternoon and evening. Over time, abnormally high blood sugar levels can decrease your body’s ability to make insulin and can harden blood vessels. The study was published in 2014.
3. Obese people who eat breakfast don’t lose more weight, but there are other benefits.
In a follow-up study, the same Bath researchers then measured the effects that eating breakfast or fasting had on people who were obese. Using the same experimental conditions they had for the normal-weight participants, they found that while obese people didn’t lose more weight compared to those who fasted, they did do more physical activity in the morning. They also ate less food throughout the rest of the day, which means that both groups ended up eating roughly the same amount of food every day.
4. People with type 2 diabetes might be better off eating a big breakfast.
Researchers from Tel Aviv University asked 18 adults with type 2 diabetes to either eat big breakfasts and small dinners (700 calories and 200 calories, respectively), or eat small breakfasts and big dinners (200 calories and 700 calories, respectively). For both groups, lunch was about 600 calories. After six days on the meal schedule, researchers measured the participants' glucose and insulin levels. Then, after two weeks, the two different groups switched conditions and conducted the experiment all over again.
The researchers concluded that when people ate the large breakfasts, their blood sugar levels were 20 percent lower after meals, and their insulin levels were 20 percent higher, supporting the notion that big breakfasts can help people with type 2 diabetes better control their disease.
5. Skipping breakfast leads to weight loss and higher cholesterol levels.
In this 2014 study, researchers from New York randomly assigned 36 overweight people to three different conditions: a high fiber breakfast (oat porridge), a no-fiber breakfast (frosted cornflakes) and no breakfast at all. After four weeks, they found that those who had fasted lost a statistically significant amount of weight compared to those who ate breakfast. However, they also ended up with higher cholesterol levels than those who had eaten porridge or cornflakes. There was no difference between the three groups in body composition, blood pressure or other cardiovascular disease risk factors besides the cholesterol levels.
So given all that, should you force yourself to eat breakfast in the morning, even if you aren’t hungry?
James Betts, the researcher from the University of Bath who conducted trials on the effects of breakfast on lean and obese participants, explains that there is no “correct” answer to this question. Rather, your choice about whether or not to eat breakfast is highly dependent on who you are and what you plan to do that day.
"If an athlete is due to run a marathon today but is not hungry upon waking that morning, then they probably should try to eat anyway,” Betts explained in an e-mail to HuffPost. “If an overweight person striving to lose weight has a sedentary day ahead and is not hungry upon waking, then there is no reason to force themselves to eat breakfast."
Michelle Bohan Brown, a breakfast researcher at Clemson University in South Carolina, takes Betts’ caution one step further and says only a clinician can accurately say whether or not forcing oneself to eat breakfast is right for an individual person, or whether it fits into their weight loss plan. Brown is set to present a review of several randomized controlled breakfast trials at the Experimental Biology conference April 6, and she says that her overall conclusion from her review is that people shouldn’t expect breakfast to have any effect on their weight either way.
"For an individual who's curious to see if they should eat breakfast to lose weight if they're overweight or obese, my recommendation would be to consult with a dietitian or physician associated with the American Board of Obesity Medicine,” Brown said. "On average, I would not expect a person to lose weight by eating breakfast, and that statement doesn't change with the association [findings] because we don't know why people who eat breakfast are associated with lower weights."
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