Friday Favorites: Is Breakfast the Most Important Meal for Weight Loss or Should It Be Skipped?

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Is the link between breakfast skipping and obesity cause-and-effect? Breakthroughs in the field of chronobiology—the study of our circadian rhythms—help solve the mystery of the missing morning calories in breakfast studies.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Breakfast is widely touted as not only the most important meal of the day in general, but specifically in relation to weight loss. This is not just a pop culture prescription from checkout aisle magazines, but an idea put forward by prestigious institutions such as Johns Hopkins, NYU, and the Mayo Clinic. Even the United States Surgeon General. “Want to trim your waist?” read a headline from the American Dietetic Association. “Try eating breakfast!”—referring to breakfast as perhaps the “best kept waist-trimming secret.” But is it true? The Duke School of Medicine’s health newsletter was skeptical: “It’s always been billed as the most important meal of the day—until now.”

While it is widely presumed that eating breakfast protects against obesity, the belief is held up as a poster child of biased distortion of the scientific record. No one can argue that there isn’t an association between body weight and breakfast. Studies have shown that obesity and breakfast skipping tend to go together beyond a shadow of a doubt, in fact, gratuitously so.

By 1998, we already had what might be considered strong evidence of an association between breakfast skipping and obesity, but researchers continued to repeat such studies to the point of ridiculousness. This meta-analysis found that by 2011, the combined P value had reached 10-42. Okay, what does that mean? Why is that ridiculous? In science, “P value” refers to the chance of getting a result that extreme if in fact there really was no such effect. How small a chance is 10-42? This is how small that number is.

In other words, the probability that the association found between obesity and breakfast skipping was just a fluke is less than the chances of winning the lottery not once, but five times in a row, and then, subsequently getting struck and killed by lightning. Okay, so the association between breakfast skipping and obesity is indeed beyond question. We know that that association is true. People who skip breakfast are more likely to be overweight—that’s true beyond a shadow of a doubt. The question, though, is whether that iron-clad relationship between breakfast skipping and obesity is actually cause-and-effect.

To illustrate the difference between correlation and causation, let me share an example of the manipulation of science by the candy industry. The National Confectioner’s Association had the gall to warn parents that restricting candy may make their children fat. They justify this outlandish claim with this study (that they funded, of course) that showed that candy-consuming children and adolescents were significantly less likely to be overweight and obese. The industry-funded researchers go on to imply that this exonerates candy. But what’s more likely? That cutting down on candy led to obesity, or rather that obesity led to cutting down on candy? In other words, the lower candy consumption may reflect the consequences of obesity, not the cause, as parents of obese children try to restrict treats.

Similarly, the finding that those who skip breakfast tend to be heavier is equivalent to saying those who are heavier tend to skip breakfast. Doesn’t it seem more likely that overweight individuals might just be skipping breakfast in an effort to eat less, rather than eating fewer meals somehow leading to weight gain? Now it’s possible that skipping breakfast could slow your metabolism or cause you to overeat so much later in the day that you’d gain weight, but you can’t know for sure until you put it to the test.

Sometimes, randomized controlled trials are infeasible, impossible, or unethical. To test to see if parachutes save lives, you can’t exactly boot half the people off a plane without them. But you could easily randomize people to eat breakfast or not, to see what happens. And, it turns out eating breakfast does not seem to affect your metabolic rate or sufficiently suppress your appetite. Most studies—95 percent—found that eating breakfast leads to the same or greater calorie intake over the day. Even when people ate more at lunch after skipping breakfast, they didn’t tend to eat an entire breakfast worth of calories more, and so ended up eating fewer calories overall. For example, feed people about a 500-calorie breakfast, and at lunch they may eat about 150 calories less than those randomized to skip breakfast, but they would still end up with about a 350-calorie surplus over the breakfast skippers. Does this then translate into weight gain over time?

Researchers at Brigham Young University randomized 49 women who habitually skipped breakfast to either start eating breakfast or continue skipping. If breakfast somehow magically leads to weight loss, then the newly eating breakfast group should benefit. But no, compared to those who continued to skip breakfast, adding the extra meal led to hundreds more daily calories consumed, and nearly a half pound of weight gain a week.

If you already eat breakfast and start skipping it, will you lose weight? We’ll find out, next.

Where did this whole breakfast-is-the-most-important-meal-of-the-day concept come from? “The Father of Public Relations” Edward Bernays, infamous for his “Torches of Freedom” campaign to get women to start smoking back in the 1920s, was paid by a bacon company to popularize the emblematic bacon-and-eggs breakfast. The role of public relations, he wrote in his book entitled Propaganda, is the “conscious and intelligent manipulation of the organized habits and opinions of the masses….” Public relations specialists thereby “constitute an invisible government, the true ruling power of our country….”

Breakfast is big business. Powerful corporate interests such as the breakfast cereal lobby are blamed for perpetuating myths about the importance of breakfast. This editorial in The American Journal of Clinical Nutrition urged nutrition scientists to speak truth to power and challenge conventional wisdom when necessary, “even when it looks like we are taking away motherhood and apple pie.” “Actually,” the editorial concludes, “reducing the portion size of apple pie might not be a bad idea, either.”

So, should we “break the feast” and skip breakfast to lose weight? Though advice to eliminate breakfast “will surely pit…nutritional scientists against the very strong and powerful food industry,” skipping breakfast been described as a “straightforward and feasible strategy” to reduce daily calorie intake. Unfortunately, it doesn’t seem to work.

Most randomized controlled studies of breakfast skipping found no weight loss benefit to omitting breakfast. How is that possible if skipping breakfast means skipping calories? The Bath Breakfast Project, a famous series of experiments run not out of a tub, but the University of Bath in the UK, discovered a key to the mystery. Men and women were randomized to either eat breakfast (defined as taking in at least 700 calories before 11am), or fast until noon every day. As in other similar trials, the breakfast-eating group ate a little less throughout the rest of the day, but still ended up with hundreds of excess daily calories over the breakfast skippers. Those who ate breakfast consumed more than 500 calories a day more. Over six weeks that would add up to over 20,000 extra calories. Yet after six weeks, both groups ended up with the exact same change in body fat. Wait…how could tens of thousands of calories just effectively disappear?

If more calories were going in with no change in weight, then there must have been more calories going out. And indeed, the breakfast group was found to spontaneously engage in more light-intensity physical activity in the mornings than the breakfast-skipping group. Light-intensity activities include things like casual walking or light housecleaning activities—not structured exercise per se, but apparently enough extra activity to use up the bulk of those excess breakfast calories. There’s a popular misconception that our body goes into energy-conservation mode when we skip breakfast by slowing our metabolic rate. That doesn’t appear to be true, but maybe our body does intuitively slow us down in other ways. When we skip breakfast, our body just doesn’t seem to want move around as much.

The extra activity didn’t completely make up for the added calories, though. We seem to still be missing about 100 daily calories, suggesting there may be another factor to account for the mystery of the MIA morning calories. Recent breakthroughs in the field of chronobiology— the study of our body’s natural rhythms—have unsettled an even more sacred cow of nutrition dogma: the concept that a calorie is a calorie. It’s not just what we eat, but when we eat. Same number of calories, different weight loss, depending on meal timing.

Just to give you a taste, the exact same number of calories at breakfast are significantly less fattening than the same number of calories eaten at supper. What?! That’s just mind-blowing. A diet with a bigger breakfast causes more weight loss than the same diet with a bigger dinner. Because of our circadian rhythms, morning calories don’t appear to count as much as evening calories. So, maybe breakfast should indeed be the most important meal of the day after all.

Please consider volunteering to help out on the site.

Video production by Glass Entertainment.

Motion graphics by Avocado Video.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Breakfast is widely touted as not only the most important meal of the day in general, but specifically in relation to weight loss. This is not just a pop culture prescription from checkout aisle magazines, but an idea put forward by prestigious institutions such as Johns Hopkins, NYU, and the Mayo Clinic. Even the United States Surgeon General. “Want to trim your waist?” read a headline from the American Dietetic Association. “Try eating breakfast!”—referring to breakfast as perhaps the “best kept waist-trimming secret.” But is it true? The Duke School of Medicine’s health newsletter was skeptical: “It’s always been billed as the most important meal of the day—until now.”

While it is widely presumed that eating breakfast protects against obesity, the belief is held up as a poster child of biased distortion of the scientific record. No one can argue that there isn’t an association between body weight and breakfast. Studies have shown that obesity and breakfast skipping tend to go together beyond a shadow of a doubt, in fact, gratuitously so.

By 1998, we already had what might be considered strong evidence of an association between breakfast skipping and obesity, but researchers continued to repeat such studies to the point of ridiculousness. This meta-analysis found that by 2011, the combined P value had reached 10-42. Okay, what does that mean? Why is that ridiculous? In science, “P value” refers to the chance of getting a result that extreme if in fact there really was no such effect. How small a chance is 10-42? This is how small that number is.

In other words, the probability that the association found between obesity and breakfast skipping was just a fluke is less than the chances of winning the lottery not once, but five times in a row, and then, subsequently getting struck and killed by lightning. Okay, so the association between breakfast skipping and obesity is indeed beyond question. We know that that association is true. People who skip breakfast are more likely to be overweight—that’s true beyond a shadow of a doubt. The question, though, is whether that iron-clad relationship between breakfast skipping and obesity is actually cause-and-effect.

To illustrate the difference between correlation and causation, let me share an example of the manipulation of science by the candy industry. The National Confectioner’s Association had the gall to warn parents that restricting candy may make their children fat. They justify this outlandish claim with this study (that they funded, of course) that showed that candy-consuming children and adolescents were significantly less likely to be overweight and obese. The industry-funded researchers go on to imply that this exonerates candy. But what’s more likely? That cutting down on candy led to obesity, or rather that obesity led to cutting down on candy? In other words, the lower candy consumption may reflect the consequences of obesity, not the cause, as parents of obese children try to restrict treats.

Similarly, the finding that those who skip breakfast tend to be heavier is equivalent to saying those who are heavier tend to skip breakfast. Doesn’t it seem more likely that overweight individuals might just be skipping breakfast in an effort to eat less, rather than eating fewer meals somehow leading to weight gain? Now it’s possible that skipping breakfast could slow your metabolism or cause you to overeat so much later in the day that you’d gain weight, but you can’t know for sure until you put it to the test.

Sometimes, randomized controlled trials are infeasible, impossible, or unethical. To test to see if parachutes save lives, you can’t exactly boot half the people off a plane without them. But you could easily randomize people to eat breakfast or not, to see what happens. And, it turns out eating breakfast does not seem to affect your metabolic rate or sufficiently suppress your appetite. Most studies—95 percent—found that eating breakfast leads to the same or greater calorie intake over the day. Even when people ate more at lunch after skipping breakfast, they didn’t tend to eat an entire breakfast worth of calories more, and so ended up eating fewer calories overall. For example, feed people about a 500-calorie breakfast, and at lunch they may eat about 150 calories less than those randomized to skip breakfast, but they would still end up with about a 350-calorie surplus over the breakfast skippers. Does this then translate into weight gain over time?

Researchers at Brigham Young University randomized 49 women who habitually skipped breakfast to either start eating breakfast or continue skipping. If breakfast somehow magically leads to weight loss, then the newly eating breakfast group should benefit. But no, compared to those who continued to skip breakfast, adding the extra meal led to hundreds more daily calories consumed, and nearly a half pound of weight gain a week.

If you already eat breakfast and start skipping it, will you lose weight? We’ll find out, next.

Where did this whole breakfast-is-the-most-important-meal-of-the-day concept come from? “The Father of Public Relations” Edward Bernays, infamous for his “Torches of Freedom” campaign to get women to start smoking back in the 1920s, was paid by a bacon company to popularize the emblematic bacon-and-eggs breakfast. The role of public relations, he wrote in his book entitled Propaganda, is the “conscious and intelligent manipulation of the organized habits and opinions of the masses….” Public relations specialists thereby “constitute an invisible government, the true ruling power of our country….”

Breakfast is big business. Powerful corporate interests such as the breakfast cereal lobby are blamed for perpetuating myths about the importance of breakfast. This editorial in The American Journal of Clinical Nutrition urged nutrition scientists to speak truth to power and challenge conventional wisdom when necessary, “even when it looks like we are taking away motherhood and apple pie.” “Actually,” the editorial concludes, “reducing the portion size of apple pie might not be a bad idea, either.”

So, should we “break the feast” and skip breakfast to lose weight? Though advice to eliminate breakfast “will surely pit…nutritional scientists against the very strong and powerful food industry,” skipping breakfast been described as a “straightforward and feasible strategy” to reduce daily calorie intake. Unfortunately, it doesn’t seem to work.

Most randomized controlled studies of breakfast skipping found no weight loss benefit to omitting breakfast. How is that possible if skipping breakfast means skipping calories? The Bath Breakfast Project, a famous series of experiments run not out of a tub, but the University of Bath in the UK, discovered a key to the mystery. Men and women were randomized to either eat breakfast (defined as taking in at least 700 calories before 11am), or fast until noon every day. As in other similar trials, the breakfast-eating group ate a little less throughout the rest of the day, but still ended up with hundreds of excess daily calories over the breakfast skippers. Those who ate breakfast consumed more than 500 calories a day more. Over six weeks that would add up to over 20,000 extra calories. Yet after six weeks, both groups ended up with the exact same change in body fat. Wait…how could tens of thousands of calories just effectively disappear?

If more calories were going in with no change in weight, then there must have been more calories going out. And indeed, the breakfast group was found to spontaneously engage in more light-intensity physical activity in the mornings than the breakfast-skipping group. Light-intensity activities include things like casual walking or light housecleaning activities—not structured exercise per se, but apparently enough extra activity to use up the bulk of those excess breakfast calories. There’s a popular misconception that our body goes into energy-conservation mode when we skip breakfast by slowing our metabolic rate. That doesn’t appear to be true, but maybe our body does intuitively slow us down in other ways. When we skip breakfast, our body just doesn’t seem to want move around as much.

The extra activity didn’t completely make up for the added calories, though. We seem to still be missing about 100 daily calories, suggesting there may be another factor to account for the mystery of the MIA morning calories. Recent breakthroughs in the field of chronobiology— the study of our body’s natural rhythms—have unsettled an even more sacred cow of nutrition dogma: the concept that a calorie is a calorie. It’s not just what we eat, but when we eat. Same number of calories, different weight loss, depending on meal timing.

Just to give you a taste, the exact same number of calories at breakfast are significantly less fattening than the same number of calories eaten at supper. What?! That’s just mind-blowing. A diet with a bigger breakfast causes more weight loss than the same diet with a bigger dinner. Because of our circadian rhythms, morning calories don’t appear to count as much as evening calories. So, maybe breakfast should indeed be the most important meal of the day after all.

Please consider volunteering to help out on the site.

Video production by Glass Entertainment.

Motion graphics by Avocado Video.

Doctor's Note

*Spoiler Alert* Ironically, breakfast may indeed be the most important meal for weight loss based on chronobiology, the effects of our circadian rhythms. While we’re on the topic, Which Is a Better Breakfast: Cereal or Oatmeal? Find out by watching the video!

And for some breakfast inspiration, check out A Better Breakfast, Dr. Greger in the Kitchen: Groatnola, and my recipe videos for a vegetable smoothie and a grain bowl from The How Not to Die Cookbook.

The original videos aired on January 6 and 8, 2020

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