In my last article I answered the question ‘what is metabolism?‘. In that article I explained that metabolism (the number of calories you burn in a day) is essentially the sum of three parts:
- Your Basal Metabolic Rate (BMR) (the number of calories you burn performing the basic functions that keep you alive).
- Your level of Physical Activity.
- The Thermic Effect of Foods that you Eat (the number of calories it takes to digest and absorb the foods you eat).
In the past I have written about the effect food has on your metabolism. However, after reviewing these articles I have discovered that some of the information in them is not 100% correct. That’s why today I want to revisit the topic of food and metabolism to explain exactly how eating can affect your metabolism.
WHICH FOODS CAN BOOST YOUR METABOLISM?
As you can see from the list at the start of this article the main way food affects your metabolism is through its thermic effect. The thermic effect of foods is relatively static. However, there are certain foods that can give your metabolism a slight boost and I have outlined these below:
1) FIBRE:- Simple carbohydrates such as sugars, white bread and white pasta are much easier to digest than more complex, fibrous carbohydrates such as fruits, vegetables and whole grain products. On top of this high fibre carbohydrates have a number of fantastic health benefits and fruits and vegetables are a rich source of vitamins. Therefore, by making the switch over to whole grain bread, pasta, rice etc, substituting some of your processed snacks (chocolate, crisps, etc) for fruits or vegetables and making fruit and vegetables a richer part of your main meals you can improve your overall health and give your metabolism a slight boost.
Why not try having a bowl of oatmeal with fruit for breakfast, a piece of fruit as a mid-morning snack, a whole grain sandwich or two for lunch, a handful of dried fruit for an afternoon snack and a vegetable rich evening meal? Not only will this be a much healthier choice and probably contain less calories than a diet which contains crisps and chocolate as snacks but it will also burn a few more calories during digestion and absorption.
2) PROTEIN:- Your body uses more energy when breaking down protein than it does when breaking down carbohydrates and fats. This was demonstrated in a study by McArdle et. al (1986) [1] which concluded that if you eat a meal consisting of pure protein up to 25% of the calories will be burned during digestion and absorption.
Most people’s diets today are rich in carbohydrates so increasing the amount of protein you consume and cutting down on the carbohydrates is another good way to provide your metabolism with a little boost. However, you need to make sure that you do not go overboard on the protein. Whilst extra protein can be beneficial eating too much places stress on a number of your vital organs including your kidneys. On top of this if you cut down on the complex carbohydrates or fats too drastically you will be missing out on a number of essential vitamins, minerals and fatty acids which can lead to a number of health problems. Vitamin deficiencies can also stop your body from performing certain functions and lead to you burning less calories.
3) SPICY FOODS:- Spicy foods give you a temporary boost in metabolism in two ways. First, certain spices have thermogenic properties i.e. they stimulate your body’s fat burning process. Cayenne, a red hot chilli pepper, is used as an ingredient in many diet pills for this very reason. Secondly, eating spicy foods raises your body’s temperature temporarily meaning that you will burn more calories as your body attempts to regulate this temperature increase.
Like with protein, eating a little more spicy food is another effective way to increase your metabolism slightly. However, spicy foods also need to be added to your diet in moderation. Eating too much can lead to stomach ulcers, an irritable bowel, heartburn, damaged taste buds and sleep problems.
4) WATER:- Drinking water does not boost your metabolism. However, it prevents you from becoming dehydrated. If you become dehydrated your body stops performing certain basic functions and therefore burns less calories. Therefore, whilst drinking lots of water does not exactly boost your metabolism it does prevents it slowing down.
WHICH FOODS CAN SLOW DOWN YOUR METABOLISM?
As I said above the thermic effect of foods is relatively constant. However, just as there are foods that can slightly increase your metabolism there are also foods that can slow it down. I have listed a number of these below:
1) ALCOHOL:- Alcohol itself does not slow down metabolism. However, it can lead to dehydration which affects your BMR and reduces the amount of calories your burn on a daily basis. On top of this many alcoholic beverages contain simple carbohydrates and sugars which require less calories to break down than more complex carbohydrates. Therefore, excessive alcohol consumption is likely to lead to a slight slow down in metabolism.
2) CAFFEINE:- Like alcohol, caffeine does not slow metabolism down itself. However, when consumed excessively it can cause dehydration which means that you burn less calories on a daily basis.
3) SIMPLE CARBOHYDRATES:- Simple carbohydrates such as white pasta, white bread and sugary foods require slightly less calories to digest and absorb than more complex, fibrous carbohydrates.
DOES MEAL FREQUENCY AFFECT YOUR METABOLISM?
In a number of my previous articles I highlighted the importance of eating mini meals to boost your metabolism. However, after reading up on the subject I found that this may not be the case and I may be wrong when it comes to the impact mini meals have on your metabolism. This post from Fitness Spotlight sums it up quite well but the general logic is that the amount you eat affects how many calories you burn through digestion and absorption. Logically it makes sense. Let’s say for example a chicken breast takes 100 calories to digest. It’s still going to take 100 calories to digest whether you eat it all at once or as part of two mini meals. Although I have said in the past that mini meals are essential for boosting your metabolism I have to admit that this was an area where I was wrong. Despite the popular rumour, meal frequency does not affect your metabolism unless the total amount of calories changes. Skipping meals will not slow down your metabolism. Eating more meals will not increase your metabolism.
However, just because the frequency with which you eat food does not affect your metabolism this does not mean mini meals are useless. As Mike (from the IF Life) says eating more frequently can help you lose weight because people are generally advised to eat complex carbohydrates and protein as part of their mini meals. These nutrients help keep you fuller for longer and are generally lower in calories. Mini meals also help reduce cravings and stop you feeling hungry meaning that you are less likely to over eat and binge on calories.
I hope this article has shown you that the food you eat does NOT have a massive impact on your metabolism. By making sure your diet is rich in fruits, vegetables and protein (without containing excessive levels), keeping yourself hydrated and perhaps eating a few more spicy meals you can give your metabolism a small kick. However, the thermic effect of food only accounts for 10% of the total calories you burn in a day so the type of food you eat is never going to have a massive impact on your metabolism. The frequency with which you eat these foods also does not have an impact. The key factor is how much food you eat and how many calories you consume. Yes eating more fibre, protein and eating smaller meals more regularly may help you lose weight BUT this is because you are eating less calories and because you feel less hungry NOT because your metabolism has significantly increased.
What do you guys think? Do you agree that the type of food does not have the massive effect on metabolism that some people think? Do you think the total amount of calories consumed is the deciding factor? Let me know your thoughts by leaving a comment.
Sources:
[1] McArdle, W.D., Katch, F.I., Katch, V.L., (1986) Exercise Physiology: Energy, Nutrition, and Human Performance Lea and Febiger Philadelphia p. 134, 135
Eating More Meals Does NOT Speed Up Your Metabolism (Fitness Spotlight)
About Tom
Hey Tom,
I am very impressed,not only with the great content (obviously), but also that you take the care to go back through old work and bring it up to speed. Many bloggers would just ignore the bad facts and carry on. I am going to follow in your foot steps and start going back through my work.
I guess it should also be pointed out that in the world of health and fitness there is constant changes and what is considered fact one year changes the next. This happens time and time again as we learn more about the body and its reactions to the stimulus we give it.
Our work is never done :)
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Tom Reply:
February 14th, 2009 at 1:22 pm
Hey Hugo – Thanks for your comments. Yeah it is quite an effort to keep all the information updated but as you rightly say new things are discovered every day. Plus the more you write the better you get at it. This makes you extra critical of your older work. There wasn’t anything majorly wrong with my original metabolism articles apart from the six meals a day thing. I just thought I could use this as a basis to revisit the topic as I thought I could do a better job this time.
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While eating smaller meals may not increase your metabolism, it is very important for fat loss which is the main reason people tune into this site. As you know, your body will only assimilate so many calories at a time. Everything else gets turned to fat and stored. Once stored, it is difficult to burn. Don’t give up on the smaller meals. It may not increase metabolism, but has many other great benefits….
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Tom Reply:
June 21st, 2009 at 12:11 pm
Hi Jeff – From what I have read eating less meals does not have that great an effect on fat burning. If you eat small, frequent meals you store less fat but you also burn less fat. If you eat the same amount of calories but split them into two or three main meals you store more fat after the meal but then you burn more fat because you have a longer fat burning period between the meals.
To address your second point I am not giving up on the small, frequent meals. In fact I still eat this way as I find it easier to cope with small portions. I am just trying to highlight that it is not the huge metabolism booster that many people (and I used to be one of those people) think.
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While it might take the same amount of calories to burn, eating smaller more frequent meals is a vital part of losing weight. If my BMR plus my daily activity remained constant, I would lose more weight the more frequently I ate. I.e.- if my BMR alone will allow me to burn 1500 calories per day, and I ate 1500 calories in one sittie like dinner time, I would gain more weight than if I spit that into 5 300 calorie meals throughout the day. My metabolism would benefit more if I ate 1500 calories of mostly vegetables with a few starches/ carbs like corn and sweet potation, and a filet of fish or chicken. And my metabolism would suffer if I ate 1500 calories of pizza and breadsticks or pasta and heavy sauces.
Furthermore, you can’t leave out the things that impact hunger. Body Chemistry (Ghrelin- which triggers hunger, and will cause people to binge if they have deprived themselves of food for longer than 4-5 hours), visual cues (fast food signs and commercials), social cues (social gatherings), cause and effect (more alcohol tends to lead to more fast food/ high fat consumption), and the fact that we need to be chewing more frequently(which is why gum is increasingly popular among those looking to shed pounds).
Some people will disagree and argue that they can go 6-7-8 hours without eating and not binge. But the question to ask them would be- how healthy are they really? Is their diet lacking the RDA of vitamins and minerals? How long have they gone without binge eating? Etcetera.
I have calculated, along with my nutritionist, what my daily caloric need is. The fact is that, for me, my weight yo-yo’d when I subscribed to the theory that a calorie consumed is the same no matter when it’s consumed or how it’s consumed. And, I’ve lost close to 90 pounds in 10 months by simply speading out my meals over the course of the day and only eating until I’m 80% full.
So, please- look at more studies- bc I’m sure there are just as many studies that say that more frequent smaller meals do effect your metabolism as there are studies that say more frequent smaller meals do not effect your metabolism.
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Tom Reply:
August 8th, 2009 at 11:05 am
Hi Jen – I’m not denying that mini meals and more frequent eating can help you lose weight. In fact I eat this way myself. If you re-read the paragraph I provide a number of benefits associated with eating mini meals. All I am saying is that portion size does not affect your metabolism.
In the example you give your metabolism would suffer. However, this is not because of the total amount of calories you are eating. It is because in the small meals you are eating a lot of healthy proteins and fibre which both help boost metabolism. In the large meals you are eating lots of simple carbohydrates and fats which have a detrimental effect on your metabolism.
I totally agree with your second paragraph. However, this is nothing to do with metabolism – it is to do with appetite control and food choices. Remember, metabolism is simply the amount of calories your body burns in a day. It is only a small part of losing weight. Controlling the total amount of calories and the type of foods that go into your body has a much bigger impact.
Overall I am all for eating small meals more frequently and I think it is probably worth me writing a full post on this topic. However, my opinion is that meal frequency does not boost your metabolism.
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eating more often, with smaller meals, does speed up your metabolism. when you eat your metabolism speeds up in order to use the food. when you dont eat for awhile your metabolism slows down as it is unsure when its next meal will be come and as such doesnt want to burn through stored energy. if you keep eating every few hours your metabolism doesnt slow down and stays at the higher rate. so yeh you’ll still be consuming the same amount of calories, but your metabolism will be going at a higher rate for longer, and as such burn more.
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Tom Reply:
January 31st, 2010 at 7:05 pm
Hey Jamie. Thanks for your comments. I too used to think that eating smaller meals more regularly does speed up your metabolism for the exact same reasons you have stated.
However, if you actually look for research to back this claim up it is very difficult to find any. Not eating for a few hours is not going to crash your metabolism. Admittedly going for long periods without food does make your body go into starvation mode but this is over a period of days – not hours.
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Tom,
Like someone said above I admire you for going back over this subject in more objectivity that many just claim boldly as fact (when it is more just hand me down mainstream media information with no real scientific backing).
As for metabolism, it is interesting to note that in a study on people fasting for up to 72 hours, the metabolism was NOT slowed down…in fact it was slightly elevated. So it it hard to believe that “skipping a meal” does anything to slow down a metabolisms (that would be a pretty poor evolutionary survival strategy if it did!).
The metabolism is more tied in with lean mass preservation, hence why subjects who do resistance training only on very low calorie diets do not have a slow down in metabolism when compared to people who just do “cardio” (who also lose lean body mass in the process). Too many people can just crush their metabolism due to cardio overload (and the cortisol environment that comes with it).
While the metabolism is a complicated system of feedback loops and hormonal responses, eating all day long is not the necessary and end all factor so many think it is for weight loss. I’ve also seen people gain weight trying to eat more often, because they eat more calories in the process.
Sure eating 6x/day…10x/day….can work, no one is claiming it doesn’t. I just ask, is it really necessary and something I want to do the rest of my life? From there people can take the facts and determine how they want to eat.
Keep up the great work!
Mike OD
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Tom Reply:
February 13th, 2010 at 6:36 pm
Fantastic summary Mike. Personally, I do try and do 5 or 6 smaller meals per day where possible. However, as you say it’s not always practical. If you go away for the weekend or have a full day of meetings at work then sometimes you just have to stick with the traditional 3 meals a day.
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Ben Reply:
April 14th, 2011 at 9:58 pm
Mike, you say “As for metabolism, it is interesting to note that in a study on people fasting for up to 72 hours, the metabolism was NOT slowed down…in fact it was slightly elevated. So it it hard to believe that “skipping a meal” does anything to slow down a metabolisms (that would be a pretty poor evolutionary survival strategy if it did!).”
Maybe I am just interpreting your post wrong, so forgive me if that is the case, but are you saying that a slowed metabolism from an extended period of not eating would be a poor evolutionary survival strategy? A slowed metabolism (whether this is actually an effect or not is another debate) is a perfect example of a great evolutionary survival strategy. You don’t need a high metablic rate to survive, you want your body fat to be slowly broken down in case you can’t find enough food to survive. Yea, nowadays that is not the case, but humans (and animals in general) weren’t looking to stay thin in the past, they were looking to make it through the winter with enough food!
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Tom Reply:
April 22nd, 2011 at 11:06 am
Hi Ben – I think Mike is best equipped to answer this question properly but my understanding is that when your metabolism slows down past its normal metabolic rate it becomes less efficient by producing less energy, failing to perform certain internal chemical reactions etc. Now whilst this is a good evolutionary strategy if you went without food for a few days it would not be so good if this kicked in after not eating for a few hours. Surely it would make hunting for food more difficult if lethargy kicked in after just a few hours without food?
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I like everything everyone is saying and I’m no expert. Just a regular guy with an opinion. The only real reference I have is in regards to lifting weights competitively. I know that many hardcore body sculptors have adhered to a minimeal frequent diet some as frequent as every two hours because they believe that it produces the best and longest fat and caloric burns. I tend to agree that doing so doesn’t necessarily boost your metabolism in and of itself. And that phraseology is really what the argument is about. It takes x calories to burn y calories of intake and that doesn’t change no matter when. However as a former body builder I know that when I eat tiny frequent meals my body never feels hunger or starvation and therefor never enters into a fail safe mode of reserving energy and therefor after a workout the boost my metabolism gets from the excersize itself that burn lasts much longer say four to six hours. Where as If my body is unsure when it’s next meal is coming might shut down the growth and healing of my muscles to conserve energy for higher brain functions which the body deems as more vital then my bicep rightly so. If I lost two hours of heightened caloric burn cause of my body’s self conservation it would drastically alter my weight maintenance. And possibly the muscular growth I was looking for which I think we can all agree that more muscle mass equals an automatic increase in daily caloric use or a higher metabolism. So although the semantics of what it means to boost our metabolism can be argued indefinitely like you yourself say eating mini meals is still the healthier (at least seemingly so) option. I just think even though you say it’s not a metabolic enhancer i say the cumulative effect is indeed a metabolic booster over time. But if you’re not excersizing then it’s a moot point anyways cause the biggest gains from mini meals (in my humble opinion) is when you allow your body to burn hotter and longer through the day. And cayanne is awesome by the way it helps for sure too. Sorry for the long comment and it’s a great article thanx.
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Tom Reply:
February 13th, 2010 at 6:28 pm
Hey Johann. No problem for the long comment. You make some good points. Whilst the mini meals idea works for many people (myself included) other people will have equal success with the standard three meals a day approach.
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caffeine is no more a diuretic than water, according to a research review article by Larry Armstrong, a professor of exercise and environmental physiology at the Neag School of Education.
“While there have been several studies done that show caffeine is a mild diuretic, there is no evidence that exercise, when combined with the consumption of caffeine or caffeinated beverages, will result in chronic dehydration, and this is contrary to the advice of most exercise physiologists, physicians and dieticians,” explains Armstrong, who has been conducting fluid balance research since 1980.
“Therefore, the health and performance of athletes and recreational enthusiasts will not be impaired if they consume caffeine and caffeinated beverages in moderation and eat a well-balanced diet,” he says.
in sum, maybe caffein might not be AS GOOD as water at rehydrating you , it doesn’t appear to dehydrate you.
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Tom Reply:
October 29th, 2010 at 12:45 pm
Thanks for the information James. I’ll have to take a more detailed look at this.
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I love the stuff on this site, I will be following you and sending people here if I am stuck with any information as its just full of it here.
Matt
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Tom Reply:
February 24th, 2011 at 12:02 am
Glad you like the site Matt and thanks in advance for any referrals.
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I think type of foods do effect the over all metabolism aspect for sure. Simple weight management can be relatively simple calories in = calories out. But, when you are looking to change your body composition such as the fat/muscle ratio in the long run, focusing on keeping the metabolism high is important. This is especially important when you looking to lose the last few pounds of fat, which is the most difficult to get rid of.
Great post between. Spicy food does have positive effect on metabolism. This is also supported by several clinical studies.:p Meal frequency is also a great way to increase metabolism provided the person can actually stick to the recommended portions for the small meal.
Navyatha.
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Tom Reply:
November 6th, 2011 at 6:05 pm
Hey Navyatha – The problem is that diet can only have a limited impact on your metabolism. The type of foods you eat only affects around 10% of the calories you burn via metabolism. Doing lots of exercise and controlling your calories is the main way you can control your weight.
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