My last post was, essentially, about using the right kind of language to convey information and what can happen if we as health care people do not choose our words carefully. I saw another example today that could be titled "why I am afraid to talk to the media if asked." It happened in this article about eating breakfast, particularly this paragraph right here:
"This first meal of the day is what can influence your appetite the rest of the day. When you skip the morning meal, it can have a huge effect on your metabolism,” she said. “By skipping breakfast, you’re kind of sabotaging yourself the whole day. You’ll have no control over your appetite and you’ll tend to overeat at lunch and at your evening meals and snacks. This can lead to weight gain. It’s best to distribute all your calories throughout the day — over four to five meals or snacks a day. To lose weight, you must really eat." (emphasis mine).
So let's talk some science to see what's wrong with this phrasing.
I think when most people hear "metabolism" in this context they are really thinking "how much fat a person is burning/how many calories am I burning off," but metabolism encompasses a lot more than that. Metabolism is something that includes all the physical and chemical processes that your body goes through to keep you alive, including keeping your heart pumping, etc. What is really being referred to here is a related concept called the metabolic rate, which basically relates to "How much food do I need and where should I get it from?" Or as I like to put it, "how much can I eat of different things and still meet my health goals?" and most of my patients put as "How much of different types of food can I get away with eating and still lose weight/control my blood sugar, etc"). Now the other problem is that we really do not have any good human studies that indicate that eating breakfast actually boosts your body's metabolic rate (Link). Sure, part of our metabolic rate does come from what is called the Thermic Effect of Food, but's it's only roughly about 10% of our metabolic rate, and that's really only going to make a difference if we just stop eating period.
So, why the emphasis on eating breakfast? One possible reason is that many of us are used to eating a diet that contains way more carbohydrate (particularly the refined, low nutrition things), that what is really good for us, and remember carbohydrate converts to glucose faster than fat or protein. Of course, we need to produce the hormone insulin to actually allow our bodies to use that glucose for energy, and more glucose means more insulin. Your glucose supply starts to fall (while you've still got plenty of insulin left in your blood) and you will hungry. As a result of this whole process (which I just gave a super-simple version of), your body gets used to having a ready source of glucose available for energy, and it's become less adapt at tapping into any fat reserves you might have. When you wake up in the morning after not eating for several hours, you will probably feel a little sluggish until you get some more carbohydrate (aka glucose) in your system. And some people try to skip that morning meal because they are trying to lose weight, or they are in a hurry, and they don't take anything to eat with them, and they don't realize how bad they feel until someone at work brings in donuts, and then their lack of energy overwhelms their judgement, and then they've eaten 3 or 4 donuts. A couple hours later your supply of glucose is depleted again, and you haven't packed a lunch, and by now potato chips sound good, etc. Now, what some of you are thinking is "Alright SkepticRD, I'm going to cut all the refined carbs out of my diet, start bringing my own snacks and my own lunch, and stop my dependence on so much glucose! And that way if I'm in a hurry or don't feel like eating breakfast, my body will just tap into those fat reserves!" And I'll say "Good for you for wanting to do better!" and then I'll remind you that the reality is that you have been dependent on that glucose for a long time, and that it may take days (sometimes weeks, sometimes years!) for your body to become so efficient that you can skip meals without feeling super hungry and wanting a quick source of glucose. (So, yeah, you better plan on having that vegetable omelette with a little fruit in the morning or grabbing that handful of nuts or eating that Greek yogurt in the morning in the mean time).
Another reason for the emphasis on eating breakfast is that depending on where you are at in life you might need to spread your intake out through the day. If you are a growing infant/child/adolescent, and trying to be an active one at that, you probably need to eat at least three times per day to provide enough protein/good fat/calories to meet your needs. If you are part of that "older adult" group, and maybe you haven't eaten so healthy throughout your life, your body might not absorb nutrition as efficiently as it once did, and it's better to spread out the food a little. If you have any kind of GI condition, you might only be able to handle so much food at one sitting without feeling cramps or nausea, so it's better that you spread it out through the day. And then there are those of us who do have to take some kind of medication for one reason or another, and you'll need to eat something to keep the medicine from upsetting your stomach.
Does the type of breakfast you have in the morning make a difference? It seems to, and the reasons are related to that whole glucose dependence thing I mentioned above. Let's say you have a large bowl of bran cereal in the morning or you have a smoothie that is just a bunch of fruit (in other words, all you had was carbohydrate). First of all, you didn't have hardly any good fat or protein to speak of at that meal, so you are probably going to be hungrier sooner (and those donuts will be tempting). If you have a history of Type 2 diabetes or prediabetes (or in my case, a strong family history of insulin resistance), you will probably get a surge of insulin to shuttle all that glucose out of the blood, and then 2-3 hours later those donuts are going to start looking really good again. If you make a point of having the above mentioned veggie omelette and fruit, etc), you will get less of a glucose/insulin surge and you will have that protein and fat to provide a longer lasting feeling of fullness.
Take home message--if eating a protein rich breakfast seems to help keep you from overeating the rest of the day, eat breakfast. But don't expect it to change your metabolic rate.