Tuesday, July 24, 2012

Is it time to eat yet?

One piece of “advice” that I frequently get questions about is how often a person needs to eat, usually framed something along the lines of “I’ve heard several smaller meals per day is better, is that right?” 
Now, if that question had “from reading on the internet that” or “my mother’s cousin’s veteranarian’s brother said” after the “I’ve heard” part, then many of you out in readerland would raise an eyebrow and probably dismiss it.  However, in my fifteen years of experience I have heard that from plenty of well meaning health care providers (particularly physicians and nurse educators) as well.  In today’s post I will not only try to answer your question but also show you how vulnerable educated health care practioner’s can be to accepting “wisdom” that has no scientific backing.
One of the main reasons that people who are trying to lose weight are told to eat more often is to “rev up their metabolism,” by which I assume they mean increase your Resting Energy Expenditure (REE), the amount of energy your body uses by you just existing.  I can see why some individuals may have gone down that path, as whenever we consume food our body does go through a process called “the thermic effect of food” (TEF) which is used to describe the energy expended by
our bodies in order to consume and process food.
  In other words, you do have an increase in your metabolism whenever you eat.  Unfortunately, it’s not as big an increase as most of us wish it was (sorry!) and when the evidence is examined, meal pattern and TEF really doesn’t seem to have an impact on whether or not a person loses weight and/or maintains that weight loss (Link).   Bottom line—eating more often will not speed up your fat burning abilities by any appreciable amount.
One of the other reasons I think this idea is still around surrounds the treatment of diabetes.  First of all, let me remind you that there are actually two main types of diabetes out there, Type 1 and Type 2.  People with Type 1 make up only about 5%-10% of the diabetes population and need to take shots of the hormone insulin to live.  (Brief refresher, you need insulin to remove blood glucose or “blood sugar” out of the blood and into your cells to be used for energy or stored as fat).  For many years (and SkepticRD is old enough to remember these) the only forms of insulin available did not really match what a non-diabetic body would produce and the insulin would be “most” active (what we can “peaking”) at odd times.  People HAD to eat multiple times per day at the same time every day or they risked dropping their blood sugar dangerously low.  Also, children with Type 1 tend to be very thin and so they would have to eat more often to get enough calories.  Fortunately we now have insulin injection regimens and even insulin pumps that allow people to have much greater meal time flexibility—but the “old way” of doing things still persists.  Boyfriend of SkepticRD has Type 1 and is the type of person that would go without food if he had something better to do; so when he first let on that he didn’t eat breakfast he braced himself for a lecture and was rather surprised (and maybe pleased) when I shrugged it off.  I think this “old way of eating for Type 1” translated to a similar meal pattern for Type 2’s, only this created some more problems.
People with Type 2 diabetes, on the other hand usually start their diabetes “career” by making TOO MUCH insulin.  Yes, you read that correctly.  In brief, people eat food—particularly carbohydrates (aka sugars/starches), it converts to glucose, and the body is supposed to make just enough insulin to handle it.  But a person with pre-diabetes or early Type 2 diabetes has insulin that doesn’t work as fast as it should (either because of genetics, excess body fat, poor activity, all of the above), so the body actually has to make MORE insulin to control the blood glucose.  Now when the body, specifically the pancreas, has to do all that overtime and doesn’t get comp time or paid extra?  Just like any employee, it will keep working but it will not work as well and eventually quit.  Now, picture an overweight type two person with diabetes eating five or 6 times per day.  His or her pancreas is going to be working overtime to keep up with all the food they are eating, which could eventually lead to less insulin production, which leads to poor glucose control, which means they have to take more medication, they one shot of insulin, then two, and then four shots of insulin, etc just to keep everything under control.  So does using one eating pattern for essentially a different type of disease process (that was less than ideal anyway) have any good evidence to support it?  Doesn’t look like it.
I also think the 6 smaller meals a day idea came from a way of thinking that states “if you let yourself go too long without eating, you will just be ravenous and eat more.”  Here is where we turn the study of evolutionary biology to see if this ultimately makes sense.  For the most of the 250,000 years that homo sapiens have been around, we haven’t had a consistent supply of food.  We evolved to build up fat and muscle stores when food is available and use it for energy when food was scare.  During the scarce times our body even evolved to function off of ketones (a byproduct of fasting) as opposed to blood glucose.  Now, as far as having food in general readily available, particular in the form of starches and sugars which give us a lot of glucose, that only accounts for a short time in human history, and our bodies haven’t caught up.  So what happens when a typical modern human tries to eat six times per day (especially if that modern human is trying to lose weight)?  They eat food, it changes to glucose, the body makes insulin to control it, and depending on their genetic history the body probably makes extra insulin than needed.  Oh, did I mention insulin also plays a role in appetite regulation?  As in more insulin, you’re more likely to be hungrier sooner?  Yes, so you eat, and then you eat again two-three hours later, and then by the end of the day you should be sick of eating, but no, you still want to have an evening meal, and then another snack before bed, pretty soon your calorie intake has maybe crept up a little higher than it needs…..So does reason for eating six times per day make sense or seem evidence based?  Doesn’t look like it to me either.
I’m also going to venture into the anecdotal here and mention that I have seen this “6 smaller meals per day” work for very few people over the years.  Some of the reasons why include 1) Some people hear this and just add extra snacks on top of what they were eating and 20 or more pounds later I am counseling them on weight loss.  2) Eating 6 times per day can be hard to schedule so people rely on convenient items like “energy” or trail mixes, or they are eating while working and not paying attention, and they wind up once again taking in too many calories. 3) As stated above, sometimes this type of pattern actually messes with your appetite regulation and you wind up not being able to make good decisions about your food intake.  Remember my post about being "hangry?"
So, for many of us, eating two to three times per day is the way to go.  I will usually lean more towards the three times per day for several reasons.  1) Most of my patients are elderly and some are very sick, so I need to make sure they are consuming enough protein and absorbing it.  Apparently the older a person gets, the better their body absorbs protein if they spread it out over three meals per day, so I need to make sure they are not trying to “make up” their nutrient intake later. 2) Since I have worked with adults, usually “middle aged” and older for most of my career, I have encountered a lot of people whose appetite regulatory system (involving other hormones like leptin, etc) is messed up for one reason or another and their body can no longer send the signals that say they have consumed enough.  People in that state often wind up relying on external cues to eat, and so they need to be on a regular schedule to learn what it’s really like to feel hungry.  3) Some of us, including SkepticRD and her patients, have to take medicine with food or we will have nasty GI side effects, so we do have to at least eat that boiled egg so we can have a good day the rest of the day. 4) Many of us are used to readily available sources of glucose and eating less than three times per day will just promote “hangryness” and make it hard to stick with a new way of eating if we are trying to lose weight.  Once you are more comfortable with your new eating plan, you might be able to skip a meal here or there without crying but I wouldn’t try it at the beginning.
Bottom line, there is no evidence to support eating 6 times per day for blood glucose regulation or weight loss.  You can put the trail mix down now.
**Note 1:  If you have had weight loss surgery or have otherwise had surgery resulting in a large part of your digestive system being removed, you might not be able to eat all of your protein requirements at three meals and 6 smaller meals might be better for you.
**Note 2: People who already eat very low carbohydrate—you are not off the hook.  If you wind up eating six times per day and consume way more protein than what your body requires, that is going to convert to glucose too.   This means that you can still over produce insulin even if you are carefully watching your carb intake.  Sticking with three meals per day will more likely help you keep your protein intake at adequate levels.
**Note 3:  I have had to give very, very brief descriptions of the wonderfully complex way our body regulates appetite and blood glucose control.  For additional reading, look here and here .  The book “Good Calories: Bad Calories” by Gary Taubes gives more details as well.

1 comment:

  1. Hi SkepticRD,

    Your essay is very informative and educates people on the healthy dietary habits. I really appreciate if you can answer the following two questions:

    1)What is the impact of rice on diabetes, over weight and immunity in human body?
    2)Based on your personal experience, what are your three key recommendations on alternative food choices?

    Sajee gopal