by Marion Nestle
Sep 21 2012

Nova: Is a calorie a calorie?

Mal Nesheim and I have just written a piece for Nova Science Now, based on our book, Why Calories Count: From Science to Politics.

Is a Calorie a Calorie?

By Malden Nesheim and Marion Nestle

Ever since the 19th century, nutritionists and the general public have accepted the “calorie” as the unit of choice for describing the energy content of food. Yet some scientists still debate whether all food calories are the same.

Do calories from a chocolate bar, for example, have the same effect on your waistline as the same number of calories from an orange? Putting it another way—and getting to a oft-invoked question in the debate—will you be more successful losing weight with calories from a low-fat diet than with the same number of calories from a low-carbohydrate diet? Or might the reverse be true? (As protein typically occurs in low amounts in foods—10 to 15 percent in the average diet—a low-fat diet is necessarily a high-carb diet, and vice versa.)

To read the rest of it and see how Nova illustrated it, click here.

  • I have heard an argument that is a little different. It says that fat makes one feel more sated than carbs thus helping one overcome the temptation to eat more calories than needed. Also low carb food costs more per calorie and that is a deterrent to eating more calories

  • a calorie is a unit of heat, not bio-available energy. Therein lies the problem.

  • I think Floccina’s point is a good one. The spike and subsequent drop in blood sugar that occurs after a high carbohydrate meal can lead to cravings and hunger pangs. I would love to see the “is a calorie a calorie” discussion address this issue as well.

  • Jason

    I think it seems to go in line that we need to consider the state of the food itself regarding the accuracy of the nutritional information (processed, how it is cooked, etc…). This article link seems to add some further insight.

  • It’s important to understand that not all calories are bad. There are calories in foods that are very good for you. It’s just important to be aware of what you are putting into your body.

  • As Dr. Joel Fuhrman: It’s the road to failure trying to eat less exercise more.

    As one of my health advocate friends states: “If I’m hungry I eat and I don’t think twice about calories.”

    That’s the beauty of eating a healthful diet that consists of great tasting food that assists with satiety.

    A calorie may be a calorie, but there’s a world of difference between a 600 calorie chocolate chip cookie and a 600 calorie “real food” meal. And, it ain’t just about weight.

    Ken Leebow
    Author of 101 Incredible Diet, Health, and Lifestyle Tips

  • Peggy Holloway

    One cannot ignore the role of insulin in fat storage and release. If you take in calories in the form of glucose, but store them as fat because of high insulin levels due to cells being insulin resistance and can’t utilize the stored fat as energy because insulin levels prevent the release of stored fat, then “calories in, calories out” is rendered meaningless. On a ketogenic diet, an insulin-resistant person will burn body fat for fuel. Calorie counting is therefore a fruitless effort, as I discovered when I adopted the low-carb lifestyle 13 years ago. Haven’t counted a calorie since.

  • Exept humans, no animal on Earth has ever needed to count calories or restrict thier portions sizes in order to stay lean. That ougt to tell us something! This is also true for animals that are sedentary. The male lion let the females do the hunting and he sleeps for about 16 hours a day. Still don’t get fat!

    The gorillas on a vegetarian diet of green leaves and some fruits are also very sedentary and spend most of their time awake eating. Still do not get fat! But put the gorillas in a zoo on a diet of Zupreems primate chow with a lot of easely digesteble starches from grains, some soy, sugar (and added minerals and vitamins) – a diet that the USDA and perhaps even Marion Nestle would applaud – and they get fat and suffer cardiovascular disease. Put them back on their natural diet and their weight goes back to normal.

    Conclusion: As long as every spiecies eats what evolution designed them to eat – from a 100 % carniovoric diet to a 100 % vegetarian diet – they do not need to count calories or restrict portion sizes. Satiety takes care of it. Put a species that is not evolutionary adapted to eating highly refined grains and added sugar on such a diet and it will derail their wieght control and force them to count calories/eat less, stay hungry in order to maintain normal wigt. But hunger defeats caloriecounting in about 95 % of the cases.

  • FrankG

    Is a calorie a calorie? Yes …of course it is.. as you yourselves explain: it is a unit of energy, expressed as the heat needed to raise the temperature of a given quantity of water by a given amount.

    You may as well ask “is a horse a horse?” or “is a pencil a pencil?” in both these cases the answer is still obviously “Yes” — although, arguably you might say that there are different types of horses (for example) while a calorie is ALWAYS the exact same unit of energy.

    So how does ANY of this get us anywhere useful in the quest to manage health and excess fat mass?

    In practical terms: if I ate 1,000 calories of butter vs. 1,000 calories of table sugar, it ought to be evident to anyone with a thinking,. critical brain that: the way each tastes, the way each fills me up so I stop eating, the way each is digested, the way any energy (and OTHER nutrients they contain) is partitioned within my body; the way they may, or not leave me satisfied between eating etc… etc… is VERY DIFFERENT!

    This is the trouble with the statement that a “Calorie is a Calorie”… it is too often used as a simplistic, blunt instrument to beat those desperate top lose excess fat mass; by accusing them of simply EATING TOO MANY CALORIES without ANY regard as to the quality of what they are eating. The sooner we stop this judgemental attitude from the professionals who are supposed to be helping us, the sooner we can start to address this ever growing issue.

  • Greg

    Yeah, unfortunately this article really only scratches the surface of the real, full question here, as many of the comments above also mention.

    There are also some contradictory parts; saying it’s about calorie intake and expenditure, while 32% of the fat in almonds goes undigested is… yeah. That makes this look like very poor coverage of the issues, basically, and jumping to conclusions.

    Secondly, the sensible and pertinent question is not “how many calories can I get away with eating?” or “how can I eat as much as possible without gaining body fat?” or other such silliness, as is often implied. Even if you decided that, say low-carb diets (or rather, high almond diets, perhaps, for example) are better on an energy storage vs. energy intake ratio, that is not what matters.

    Could you people please stop wasting time money and words on farting around at the edges with taxpayer money, with studies that are not real world applicable, trying to answer yet again only intermediate questions that we already are pretty sure of the answer too, and not what really even what ultimately matters?

    Seriously. I totally appreciate that you start with the easy study like this one in a metabolic ward with the obese patients. But seriously. Things do not have to be this uncertain; cut to the chase already and so one that measures actual body fat weight, not total body weight during the study, so you can have some actual confidence in the freaking results.

    I know it costs more, but seriously. All things considered, things can clearly be done much better here, and this sort of thing really makes scientists working on these issues out to be a bunch of incompetent buffoons more than anything, even though I know that’s not really what is up. It is pretty exasperating that you seem so utterly incapable of getting on with things and doing something that is actually bottom line useful.

    We don’t need ten studies that only slightly help a teeny bit, published over a decade we need to actually answer the fucking questions.

  • Anthro

    Oh dear–so much criticism of such a simple conclusion, eat less, preferable real food, mostly plants and you WILL lost weight.

    As long as people go on fighting this simple (but never all that easy) advice with elaborately constructed “theories” that stand little chance of ever being scientifically verified, they will continue to live in denial of simple facts.

    If you lost weight on a low (fill in the blank) diet, it is likely because you are, one way or another, eating LESS. If the diet is odd or limited in variety, you will have a hard time staying with it, whereas over time, it is possible to learn to eat smaller portions, eat more often at home, give up some favorites and limit others to special occasions. It won’t always work but if you use the scale regularly you can catch it in time to back up and make some adjustments.

    A note: We are not actually carnivores, but rather omnivores–which means that we can eat just about anything for survival, which is what we did in our “early days”.

    We scrounged around for whatever was available in our environment. We used calories moving around and didn’t find an over-abundance of honey pots or Cheeto trees–or even all that much meat. We scavenged bits from other predators when we could and figured out how to catch some critter–with limited success in most cases. This protein helped sport the growth of our brains, but not because it was obtained in huge or regular quantities, but because we were flexible enough to use it when we found it one way or another.

    There’s more to this story, but space here doesn’t allow for Anthropology 101. It is clear that the views of experts don’t matter much to most of you and some of the thinking is so muddled that I (shock!) am at a loss for words.

    I, for one, enjoyed the article and thought it brought some clarity to a confusing issue–but then I have read the book it was based upon and have a modicum of respect for the combined many years of education and experience that went into its writing.

  • It seems to me the $50K question is which foods promote overeating and which foods promote healthy weight maintenance or weight loss.

    The fact that eating less results in weight loss is tautological.

    Why are humans in advanced industrial countries that only animals that (try) regulate their weight with the neocortex rather than the basal ganglia and limbic regions of the brain?

  • Funny, @Jason, I was just going to post that link!

    The problem is, calories aren’t really the problem at all – behavior is the problem. We can’t change the intake-outgo without changing behavior – and in order to change behavior we need to understand it.

    Measuring energy may be a good way to track how food relates to weight gain and loss, but it doesn’t help explain how to stop people from eating too much or to keep them from moving too little.

  • Jason

    I agree that behavior is one of the key problems, and that one of the major controversies is whether the government needs to step in, as also pointed out here on this website as well. I also see an underlying problem that most people don’t understand what true hunger is, and feel that the attitude now seems to be that any feeling of hunger needs to be “fixed” by eating; something encouraged by the food industry… 😛

  • Margeretrc

    @anthro, “eat less, preferable real food, mostly plants and you WILL lost weight.” True. The problem still lies with HOW to eat less without being hungry or counting calories. I agree with Per Wilkholm, Frank G and Peggy Holloway. Let evolution (and hormones) be the guides as to how much of what real food we eat.
    A calorie is a calorie, but how our bodies use the calories we consume depends very much on where those calories come from. As Michael Pollan says, the “mostly plants” should be mostly leaves (not seeds) and other parts that grow above the ground. That leaves plenty of calories for the more satiating protein and fat–which will keep one from over eating.

  • jonathanwr

    The “can”-s and “should”-s as far as diet is concerned are so rampant that it’s hard to tease out what’s actually proven to work and what isn’t.

    What actual studies (not anthropological arguments) show:

    *a ketogenic diet treats intractable epilepsy in children
    *a low fat diet in postmenopausal women (WHI) does not reduce the risks of heart disease, diabetes, and breast or colon cancer over 8 years. the same diet exacerbates diabetes in women who already have it and seems to raise secondary CHD events.
    *a Mediterranean diet reduces heart disease risk by 30%
    *low fat vs low carb diets both lead to weight loss, but the latter has a greater positive impact on total lipids and glucose levels (a plus for diabetics).

    Vegetarians DO have a lower heart disease risk than omnivores. But whether that’s actually due to the lack of meat or some other factor (such as less junk food and/or more physical activity) isn’t clear.