Can Calorie Counts on Food Labels Be Trusted?

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    Mar 04, 2013 4:04 PM GMT
    http://www.care2.com/causes/can-calorie-counts-on-food-labels-be-trusted.html

    In many cases, no, calorie counts on food labels cannot be trusted, and for more reasons than one.

    In this New York Times Op-Doc, filmmaker Casey Neistat shows just how unreliable they can be. Enlisting the services of a science lab equipped with a calorimeter, he tested five random samples selected from among foods he might eat on any given day. Four of those five had more calories than their labels said they did, including a pre-packaged spicy tofu sandwich that had nearly double the amount. A Subway sandwich was the only one that came in under the stated calorie count.

    Some scientists are also questioning the very system we use for measuring calories in foods, the century-old Atwater system that assigns 4 calories per gram for proteins and carbohydrates and 9 calories per gram for fats. That system does not take into the account the fact that the degree to which our bodies metabolize foods varies with the type of food, the level of processing it has undergone and the “energy status” of the person eating it.

    For example, some of the fat in almonds and certain other nuts goes undigested and passes through our bodies as waste. A 2012 study led by USDA scientist Janet Novotny found that the calories we get from a one-ounce serving of almonds is 32 percent less than the Atwater values estimate. So when you eat a large handful of almonds, you may only be taking in 109 calories as opposed to the 161 calories listed on the label. As NPR reports, scientists suspect that this is because we don’t chew them enough to fracture all the cell walls and release all the fats.

    Food processing also affects the number of calories we actually absorb from a food. Rachel Carmody, a postdoc at Harvard University who organized a symposium called “Why a Calorie Is Not a Calorie and Why It Matters for Human Diets” at the American Association for the Advancement of Science’s annual meeting last month, told NPR that she wants people to “realize that something that’s more highly processed is going to represent more calories than in a less-processed form.”

    Based on experiments conducted in her lab, she attributes the net energy gains “to higher rates of nutrient assimilation in the small intestine as well as reduced diet-induced thermogenesis, the metabolic cost of digestion.” It is a lot easier for our bodies to extract nutrients and calories from cooked and processed foods than from whole and raw foods, and those foods also require less energy for our bodies to digest.

    These aspects of digestion are not represented in the Atwater factors typically used in the determination of metabolizable energy value. Thus researchers who report Atwater-based energy values as well as consumers who utilize nutrition labels to manage their caloric intake will necessarily underestimate the energetic gains associated with a processed diet.

    Still, other experts like Malden Nesheim and Marion Nestle, co-authors of “Why Calories Count,” argue that “for most foods, estimates based on Atwater values are close enough.” And “until research convinces us otherwise, we believe a calorie is a calorie.”

    An awareness of the calorie content in foods is supposed to help us make more informed choices and perhaps cut back a bit on what we eat. That’s the point of the new federal requirement that calories be posted at food establishments across the country, which is expected to go into effect at some point this year. We’ll have to wait and see whether or not across-the-board calorie labeling will help Americans lose weight or improve health outcomes. But if it’s going to do any good, as suggested in the Op-Doc, don’t we at least have to start with calorie counts that are a little more reliable?
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    Mar 04, 2013 6:08 PM GMT
    It's a bit of a silly argument from some rather stupid people.

    The composition of foods is not all that precise. The most you can expect from label values is that out of many, many servings, the values would average out to the published value. Values posted for restaurant meals couldn't possibly ever be more than very fuzzy estimates.

    The only way it would be possible to really control those values precisely would be if you are manufacturing an extremely highly processed product from a set of expensive homogenous powdered and liquid products. Nothing that most people would want to eat.
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    Mar 04, 2013 9:51 PM GMT
    Meanwhile in the UK we are eating meat labelled as one animal that actually comes from a different animal entirely. So we have given up looking at stuff like calories haha.
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    Mar 05, 2013 2:48 AM GMT
    No. This is why I prefer to eat mostly healthy foods instead of counting calories that may or may not be correct.
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    Mar 09, 2013 5:52 PM GMT
    bus9ja2d saidMeanwhile in the UK we are eating meat labelled as one animal that actually comes from a different animal entirely. So we have given up looking at stuff like calories haha.


    Yeah, but good, lean horse meat is a better source of nutrients that most beef. ;)
  • Medjai

    Posts: 2671

    Mar 09, 2013 5:56 PM GMT
    Lets put scaled calorie labels on drinks too, since it costs energy to bring them up to temp!

    It's never been an exact science. Since there are only three major macronutrients we derive energy from, and the Atwater measurements are fairly accurate, these numbers give a good, functional baseline. But there will always be variation.

    If there is an issue with labeling accuracy, take it up with the companies misrepresenting, not a system that isn't broken.