Busting Food Myths with Nicole Senior

Myth: Some foods have negative kilojoules (calories)

Nicole Senior

Fact: It is impossible for a food to use more energy to digest than it contains. To create a kilojoule or calorie deficit in your body, eat a balanced diet with plenty of vegetables and be more active.
We’ve all heard the stories about celery taking more energy to digest than it actually contains, but is this true? Moreover, does it make any difference in the quest for healthy weight loss? My answer is ‘no’ to the first, but ‘maybe’ to the second.

If thinking whole fresh foods such as vegetables contain negative calories helps you to eat more of them, go ahead. The health benefit of the end certainly justifies the mistaken means by which it is achieved. If, on the other hand, the overweight and vulnerable rely on a crazy unbalanced diet featuring eating these foods in large amounts to the exclusion of nost others, then this myth should be nipped in the bud.

Although celery does not take more calories to digest than it contains, it naturally low in kilojoules – a helpful characteristic of most vegetables and the reason why sensible weight loss diets emphasise eating plenty of them. Not to mention their grocery list of other health benefits. Of course their low-kilojoule status is undermined by eating them with peanut butter or cream cheese on top (is there any other vegetable that better lends itself to filling up the middle with something tasty?). Although in my profession it may be cavalier to say it, celery doesn’t taste that great on its own. Lower kilojoule options to ‘fill the gap’ are tomato salsa or chickpea dip (hummus). My favourite way to enjoy celery is sliced in a stir fry with lots of other vegetable friends and some lean chicken, beef, pork or tofu, nestled on a bed of brown rice or noodles.

At the heart of many nutrition myths is a kernel of truth, and in this case it is the notion that whole foods rather than overly processed foods take more digestive effort and in some cases hold back a little of their energy because it’s too hard for the body to liberate. The extra digestive effort starts in the mouth as some foods need a lot more chewing. This is very positive because of the energy it requires, the way it slows down eating to allow the brain to register satiety (fullness), and of course the direct effect on strengthening the jaw muscles and massaging the teeth and gums. The hard and complex structure of some foods such as wholegrains, nuts and legumes actually prevent all their nutrients (and kilojoules) from being released during digestion and some simply pass straight through. This could be a reason why high fibre diets and diets containing nuts help with weight loss. Conversely, many processed foods are easy to overeat because they go down so easily. Think of fluffy white bread, donuts, cupcakes, mash potato, ice-cream and even juice. In the case of fluffy white bread and mashed potato, these low-digestive-effort foods have a high GI to boot. For many reasons, it’s worth working harder for your food.


Back to the celery. Whenever you encounter a myth which implies doing something as simple as eating celery (or whatever) will help you lose weight, ask yourself the following reality check questions:
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