by Marion Nestle
Jan 6 2010

How many extra calories cause weight gain?

For years, some people – not me – have been saying that eating one extra 50-calorie cookie a day can make you put on 5 pounds per year.  This calculation comes from basic math: if about 3500 extra calories make you put on a pound of body fat, then 50 times 365 is 18,250 extra calories which, divided by 3500,  equals about 5 pounds.

This never made sense to me.  It is impossible to know how much you are eating each day within 50 calories let alone how many calories you are using in daily activities.  Yet people used to be able to keep their weight steady without thinking about calories at all.

This is because the body regulates weight and can easily compensate for such small changes in calorie intake or output with small changes in metabolic rate.  It takes more calories to move heavier bodies, and fewer to move lighter ones.

For years, I’ve been thinking that it must take a lot more than 50 extra calories a day – I guessed hundreds –  to make people gain weight.  I thought this for two reasons:

First reason: Portion sizes have increased greatly in recent years, and larger portions have more calories.  Sometimes, they have a lot more.  Foods eaten outside the home often have more calories in them than anyone suspects.

That’s why calorie labeling matters.  Labeling may underestimate the actual calories present in a food according to Tufts researchers (see this week’s Time for commentary and also see the industry response).  But even so, a new study shows that labeling encourages people to cut down on food intake, at least at Starbucks.  Make that two new studies: one from the Rudd Center at Yale comes to the same conclusion.

Second reason: I keep hearing from pediatricians who treat overweight kids that they have kids in their practices who drink from 1,000 to 2,000 calories a day from sodas alone.  I can’t judge whether these figures are correct or not, but several different kinds of studies suggest that many people today are eating a lot more calories than their counterparts of 25 years ago.

Now Martin Katan and David Ludwig have done the actual calculations in a paper in this week’s JAMA titled “Extra calories cause weight gain–but how much?”  Their conservative estimate is that it would take an excess of 370 calories to gain 35 pounds in 28 years.   To become obese in 25 years, you would need to eat 680 calories a day more than you expended.

To become 58 pounds overweight at age 17, they predict that a child would need to overconsume 700 to 1,000 calories a day from the age of 5 or so.

These figures are quite consistent with what those pediatricians were telling me.  By other estimates, average caloric intake has increased by 200-500 calories a day since the early 1980s, along with a 700 calorie-a-day rise in the availability of energy in the food supply (from 3,200 to 3,900 per day per capita).

As Katan and Ludwig conclude:

small changes in lifestyle would have a minor effect on obesity prevention.  Walking an extra mile a day expends, roughly an additional 60 kcal compared with resting – equal to the energy in a small cookie.  Physiological considerations suggest that the apparent energy imbalance for much of the US population is 5- to 10-fold greater, far beyond the ability of most individuals to address on a personal level.  Rather, an effective public health approach to obesity prevention will require fundamental changes in the food supply and the social infrastructure.

This is because on the personal level, prevention of weight gain means eating hundreds of calories a day less.  Moving more, useful as it is, will not do the trick unless people eat less as well.

On the societal level, we need measures to make it easier for people to eat less.

I can think of a bunch of examples.  You?

  • Darryn

    I agree. Labeling, and education around labeling is critical.

    I also think we need to “re-educate” people about portion sizes. It’s interesting that (prior to the soda deluge) most of us as kids had an innate understanding of how much we needed to eat to maintain energy; we just ate until we were full. However, it seems that restaurants (as you’ve pointed out) and the food industry have led many people to believe that “bigger is better”. I think that actively re-educating people about what a portion size really looks like could really have a beneficial impact.

    I “re-educated” myself on portion sizes recently and was surprised how distorted my perceptions had become.

  • Sarah

    Aside from portion control, there is also the issue of snacking. If one works at an office job, snacking is a main concern. This is anecdotal observation, but it may be that the psychological ramifications of feeling tied to an area (cubicle/desk) result in a constant vigilance for food. I’ve known way too many coworkers who keep boxes of snacks deskside because they feel too busy to stop and eat a full lunch. Likewise, they want to make sure they have “enough to eat” though bringing a healthy lunch to store in the fridge would be just as easy.

    As for myself, I’m quite educated on portion sizes and I’m overeducated on nutritional information–and yet I snack, and snack, and snack…

  • catherine

    For me portion contol is all about eating slowly. My body knows when it is “full”, but only if I give it time to catch up.

  • Joe

    Thanks for writing this blog – it’s extremely helpful.

    With the talk above of “extra” calories adding contributing to weight gain over long periods of time, I have to wonder whether the generally accepted baseline caloric intake is on point.

    After gaining about five pounds, I started tracking my caloric intake – in an average day, without dieting or eating any more healthily that I had been, I was taking in about 60% of the calories baseline for a person of my age, height and weight. One would think that would lead to continued weight loss, but my BMI has been in the 22-23 range for years. Odd.

  • Robyn M.

    If I understand the point of your above post, then small quantities of additional calories aren’t sufficient to gain weight–it takes something more substantial than just 50 or so calories over what you expend, because the body can maintain weight in the face of small caloric fluctuations. So I’m curious if the converse is also true. That is, in order to lose weight, does one need to also take in substantially fewer calories than expended? Will a 50 calorie per day reduction result in a net weight loss, or will it take something closer to a 300 calorie reduction?

  • Jennifer

    Very interesting. Maybe I’ll quit kicking myself over having a cookie every now and then!

    On a more serious note, the ways to encourage people to eat less are almost inexhaustible, but it’s probably much harder to achieve than we can conceive.
    Certainly portion sizes are a big part of it. But our entire existence has been built to accomodate our growing appetites. Perhaps smaller plates and other dinnerware would help, or smaller fridges and pantries. The supersizing hasn’t stopped at food.

  • Benboom

    It is true, however, that unless you eat while you walk, that time you are walking is snackless. Perhaps that’s one reason why exercise seems to help: unless you eat while you’re doing it you are actually dieting at the time. For people who eat constantly throughout the day that could make a difference. Just a thought.

  • bronislava

    A new school opened in my neighborhood. A dunkin donuts immediately opened next to it. Down the street all the convenience stores, starbucks,etc. make half their money selling junk food to the kids.

    Portion size depends on what you are eating. I made miso soup with sliced mushrooms and “somen” noodles (similar to angel hair) for lunch. It was a big bowl, but half of it was water.

    Some research suggests eating “heavier” foods, like apples is helpful. (People tend to eat a consistent weight of food daily, while calories fluctuate day to day.)

    Maybe give the school kids some “vouchers” they can use to buy lunches and snacks at local businesses, but are only redeemable for healthy foods?
    Maybe some places would open that sell affordable healthier convenience food such as noodle bowls, falafel, and juice bars.

    It might be unfair, though, as more affluent kids wouldn’t need to use any food vouchers. Still, it’s the poorer kids with the highest risk of obesity and nutritional deficiency.

  • Cathy Richards

    Altho Marion’s post clearly said we need a change in our food supply and our social infrastructure, many of these comments are still stuck in the “you just have to make the right personal choices” rut.

    Read the end of her post again — the degree of change required is “far beyond the abilities of most individuals to address on a personal level”.

    Knowledge and personal responsibility are important, but it’s a pie in the sky utopian view of humanity to expect it to be enough to counteract a truly horrendous food environment. The 10 Commandments don’t the majority of us from coveting or whatever, so how could nutrition knowledge be expected to be the only answer to the devilish profit-mongering food industry?

    We need our environment (workplaces, grocery stores, neighborhoods, schools, home pantries — everything) to support that personal responsibility rather than undermine it. Even Dietitians succumb to the power of the food environment, so knowledge and will power are not enough.

  • EdSanDiego

    We spent $40bn last year on weight loss products, lotions and potions and we ate more? OMG, someone do something.

    Lets do the math.

    $40bn per year x another 25 years = nothing close to the healthcare costs we have to pay to deal with the fallout from obesity.

    We do the same things each year and we are still expecting a different result. In some countries that would be a sign of insanity and all the regulators would be locked up.

  • Emily

    I think I am the only one of my friends who actually makes salad dressing. This is apparently very impressive of me. Everyone else thinks this is simply something you buy, even though making it takes seconds, and homemade versions are healthier and tastier. But we’ve let “convenience” (marketed to us with huge advertising budgets) make us think salad dressing, pasta sauce, and even peanut butter & jelly sandwiches are hard to make, so throw another package into the shopping cart. Insidious!

  • Anthro

    Marion’s point that this problem is largely beyond the individual gets her called a “food nazi” by conservatives, but, of course, she is right. Only by developing an extremely cynical view of the food industry over many years have I been able to walk through a store (even a “health” food store) and get only what I need to maintain my 1000 calorie/day regimen. I read labels thoroughly and really look at the number of portions in a container–shocking! I am older, of course, so I am accustomed to preparing my own food and packing a lunch, etc., but I see young people (including moms) loading their carts with everything packaged and snack-y. It’s getting harder to find anything that ISN’T in a package, including lettuce!

    Of course I have a goody now and then, but the other day I was at one of those Starbuck’s kiosks at Target and was thinking of getting a cookie because it was fairly small by modern standards–then I saw the little sign (only the cookie had a sign) which said 360 calories! You can bet I passed up that cookie. Even though I read labels and count calories every day, I was surprised at the calories in that cookie. A few years ago, of course, there was no Starbuck’s at Target. I think they are experimenting with the calorie listing and according to the research you mentioned, I’m not the only one who can say “no” when properly informed. I did get a little packaged biscotti that only had about 110 calories.

  • Amy S

    You can certainly see the smaller servings taking hold in upscale restaurants. It also allows a restaurant to lower its prices, which in this economy is a big plus if guests can have a wonderful dinner and not spend half a paycheck doing so.

    But where it really matters, when we honestly talk about obesity, is not what the wealthy are eating, but what is being fed to the poor. Federally subsidized lunches that I wouldn’t feed to my dog, with few fresh vegetables for kids. Or fast food, which is one of the few ways the poor can have a full stomach on very little money (have you seen those dollar menus?).

    I volunteer for Days of Taste, a program sponsored by the American Institute of Wine and Food, where 4th grade kids are taken to our city’s farmer’s market and taught about where food comes from by local vendors. Then they are given $1 each and grouped in small groups to go into the market and purchase fruits and vegetables to make a pasta salad with.

    I cannot tell you how many kids say “Vegetables are yucky” at the start, and then ask for second helpings when it’s all completed. The sad part is that these kids will return to homes that do not value fresh fruits and vegetables in their diet.

    I have spoken to local committees about how our school could better service their students in their dietary day – a salad bar. But every time it is explained that a salad bar would not be possible with the federal constraints on subsidized meals.

  • Tom Kovacevich

    Thanks for this post, I have always thought the same way on weight gain and incremental calorie counting. Nice to hear an expert lay it out.

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  • rjm

    I don’t see why those estimates are peculiar. The same methods used to make predictions on how much weight would be gained if an additional 50 Calories were eaten are used to lose weight too. As such, I use those methods everyday and stay around 4% body fat(last measured it was 3.6%). I control all my food intake and follow a strict workout regimen(Calories burned mostly from running and also from weight lifting: both calculated as a function of appropriate MET values and body size).

    The key idea is consistency. The subjects in your example must first take in enough Calories to support their current weight, then the next day would include the previous + 50, then the next would be previous + 50*2: this is an artihmetic progression. The common difference being 50 and their initial weight the starting value of the sequence. If this is followed, consistently, they will have acquired extra mass equal to the extra Calories taken from foods. Measured in Calories, they will come out to being about equal.

  • Liz T

    This makes so much sense to me, and I believe it also applies to weight loss. Many weight-loss guides state that cutting out one small thing a day will result in a loss of however many pounds over a year, and my experience is that it’s simply not true.

    As someone who has been on a 20-pound gain and loss roller coaster for over 20 years, it takes a hell of a lot more than cutting 100 calories a day to get the number on the scale to start to drop. And the older I get, the harder it gets.

    I pray for a magic bullet but I know that it all comes down to hard work.

  • rjm

    When it comes to weight loss, you need to count calories. Otherwise, your situation is like traversing a maze with a blind fold on and hoping that you’ll reach the exit. Of course, exercise also accelerates the weight loss process. The key is to consistently stay in a caloric deficit. In addition to counting calories, you need to know your BMR, and be able to effectively measure how many calories you burn through exercise. Above all else, you must be honest with yourself. Too many times I’ve talked to people that were not honest with themselves. They would have me believe that they were taking in far less calories than what their body size suggested they were taking in. When confronted, they would, with reluctance, admit that there were other foods(oh, a little wine here, a little of this there, etc.).

    Anyone that follows the above recommendations will lose weight. For some reason, people have a tendency to treat the situation like there is “magic” involved. If you eat too much, then the excess energy from foods has to go somewhere. Where? Your body will store it in the form of triglycerides. When your body needs energy for performing a task, one of the places it will get it from is from the triglycerides(among other places).

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  • Drew

    In my nutrition classes we learned about a setpoint, that people can’t lose weight because of their body fights for equilibrium. Since few people are looking to gain weight, you never hear people complaining about a setpoint that prevents weight gain. But it seems quite reasonable that we are gaining weight not because we are slightly off balance over a very long period, but that we are way off. Thank for laying it out in this post.

    I see the plain evidence that too-big portions are the guilty party, but I question whether it can be used as an effective message. Clients are turned off when the blame lands on them and their lack of self-control. Fairly, I’d say. Cutting portions down to size and leaving the table feeling hungry is far too ascetic to be a long-term solution. Far better to look at the quality of foods, allow people to eat portions as they please of low energy dense foods and leave the table content, but with far fewer calories. To me this seems like a approachable message that turns the nutritional professional from a foe into an ally.

  • Lori

    Portion sizes are key to preventing weight gain . Most people grossly underestimate how much they really eat. A muffin sold at the coffee shop today is 3 times larger than the muffin sold there 15 years ago. And yet, people today eat that muffin as a snack.

    A key sentence in this article is “700 calorie-a-day rise in the availability of energy in the food supply “. That muffin is part of the increase.

    I can remember my grandmother not giving us a coke unless we had already had a glass of water to quench the thirst. And that was IF she had the coke in the house AND it was an 8 oz bottle (ok can’t really remember but the bottles were smaller). Kids today drink Gatorade as if it were a healthy drink – more than one bottle a day. Again, part of that 700 calorie-a-day increase.

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  • Karen

    Last year, I lost 45 lbs of extra weight I was carrying and I feel better than ever. Part of my journey to better health was reading food labels and paying attention to calorie counts. I refused to stick my head in the sand anymore. On the very occasional visit to a restaurant, I made a point to look online for nutritional information and calorie counts of the menu items. I was shocked and disappointed to find that many common chain restaurants either didn’t have the information I needed for an informed choice, or had it available online, but not available when I arrived at the restaurant. I shared my frustration wtih my friend who worked for the Center for the Science in Public Interest in DC and she invited me to testify before a committee of the Maryland Legislature. In March of 2009, I sat in front of a committee of elected officials and asked them to consider making menu labeling mandatory in Maryland. Unfortunately, it never made it to the floor for a vote, but I’m very pleased that the county in which I reside voted to make it mandatory. Hopefully, our state will soon follow. Here’s a link to my testimony:

  • interview tips

    according to me obesity can be controlled mainly by strong determination in mind, food control is necessary along with mind control

  • Holly

    As important as portion control is, limiting exposure to restaurant food is crucial, too. The amount of oil and butter used in most restaurants is insane. Even “steamed” vegetables can contain upwards of 4 tablespoons of butter in a rational portion!

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  • CalorieTips

    I agree with most of the respondents to this issue. The size and calories associated with these portions has drastically changed and increased over the last 2 centuries.

    What has helped me is learning about TEF (Thermic Effect of Feeding ) and TEA (Thermic Effect of Activity and/or Exercise). These two factors contribute to how your calories are burned and how your body stores them after consumption.

    There’s a more in-depth discussion of this and other calorie factors on

  • jennyct

    that’s an excellent question… also, why when we go from our weight loss target to maintenance, do we gain weight too quickly? We have to add back only a little each week.

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