bite my words

Dispelling nutrition myths, ranting, and occasionally, raving


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Fat does not equal fat

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The article: Anyone Silly Enough to Think Fat is Good for You Needs to See This Brain Study made me want to scream and scarf a bag of potato chips out of spite.

The article reports that the study found that body fat doesn’t just sit around your midsection, it also affects your cognitive function. This lead them to the conclusion that recent reports that dietary fat has been wrongly demonized are incorrect.

What’s my problem with this? One, body fat and dietary fat are not the same! You can become obese by consuming too many fat-free foods. Dietary fat does not equal body fat. The study was looking at  body fat not dietary fat. This means that we can’t go blaming butter. Two, the study was done on mice. Mice are not humansYes, it’s quite likely that excess body fat has negative effects on many aspects of your system. However, we can’t make the leap from a study on mice to humans. And we most certainly can’t make the leap to dietary sources of fat.


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The “real food” fallacy

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All of a sudden, it seems that Zoe Harcombe is everywhere. She was providing ludicrous nutrition advice for sufferers of yeast infections (thanks @RD_Catherine for the link). Sorry y’all yoghurt won’t cure yeast infections. Yes, choosing a yoghurt with probiotics is great for overall health but it’s more because of the by-products produced by the bacteria (e.g. B vitamins) than because of the bacteria themselves. Unfortunately, most of the bacteria in yoghurt will not survive your stomach acid.

What I really want to address though, is her popular article in the Daily Mail (thanks to @ERHWG for sharing the article and her rage): Diets Make Us Fat. The Solution is Simple. The basic premise is that we need to eat “real food” as opposed to fake  “manufactured food”. Calories don’t matter, and we shouldn’t be counting them. All that matters is eating “real food”.

But what is “real food”? I don’t think you’ll find many dietitians who disagree with the importance of cooking and eating more vegetables, fruits, and minimally processed foods for overall health and weight loss. However, I don’t think the division between “real” and “fake” food is particularly useful. Nor is the vilification of whole grains. Grocery shopping is complicated enough and people are hard-pressed for time. Making them feel guilty for buying anything in a package is not going to help them to adopt healthier habits.

It’s also possible to be over weight when consuming a “real food” diet. You know why? Because calories do matter. I’ve met plenty of people who are over weight who eat very healthy diets. Simply telling people that if they eat “real food” is not going to solve the obesity crisis. If I was over weight and someone gave me this advice I would be insulted. Not everyone who is over weight or obese is subsisting on a diet of big macs and kit kat bars. Consuming more calories than we need, regardless of the source, will result in weight gain.

Finally, the reason that diets don’t work is because they’re short-term fixes. Not because people are necessarily consuming the wrong types of foods or because they’re counting calories. The problem with diets is that they have an end date. They are not sustainable lifestyle changes. The other reason that they don’t work is because our food system is broken. Our environment is structured such that the unhealthy choice is the easiest choice and it’s a lot of work not to be over weight. Placing the onus on the individual and suggesting that if they only stopped counting calories and ate “real food” doesn’t even come close to addressing the true societal roots of the obesity epidemic.


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Low-fat vs low-carb

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There’s a lot to unpack from this Daily Mail article a friend alerted me to. The premise: a couple of identical twin doctors decide they need to lose weight. In order to determine which fad diet is better, one goes low-carb, the other goes low-fat. The fact that they are genetically identical and maintained similar levels of physical activity means that they assumed any differences observed would be due to diet. While there is merit to using identical twins in research studies it’s important to note that this was not a scientific experiment. One subject in each group doesn’t lead to robust findings. Other issues: obviously both men knew which diet they were on and there was no control group. So, this wasn’t good science but it’s still possible that we could learn something interesting from their little “experiment”.

Before we look at what they “learned” from the experiment there are a few things in the article that I want to touch on. Firstly, the headline states that “one twin gave up sugar”. Well, yes, but this twin also restricted all forms of carbohydrate, not just sugar. The twin who went on the low-carb diet thought that it would be effective because of the insulin hypothesis of weight gain.

Because these carbohydrates are highly refined, they tend to raise blood sugars and blood insulin levels quickly.  This will tend to cause weight gain and obesity.  This is known as the Carbohydrate-Insulin Hypothesis (CIH), and is the basis of the Atkins diet and many other low carbohydrate (Dukan) and very-low-carbohydrate diets (ketogenic diet). (1)

While it sounds convincing, we know this hypothesis to be incorrect. For one thing, there are many people/populations who consume high-carbohydrate diets and never develop obesity. For another, insulin on its own does not cause obesity (2). Minor quibble, really, but as doctors discussing weight loss they should have their facts straight. Obesity is complicated and there’s no smoking gun out there.

An important point that they make is:

…despite being doctors – I also have a degree in public health – neither of us knew much about losing weight and eating healthily. 

These topics fall between the cracks at medical school. Yes, we understood biochemistry and food metabolism, and knew a lot about the consequences of being overweight. But which diets work, why we eat too much and why losing weight is so hard don’t sit within any medical speciality.

Pity that they didn’t take the opportunity at this stage to point out that this means that assuming your family doctor will tell you if your weight is a health concern or that they are a good resource for weight loss are dangerous assumptions. If you are concerned about your weight being a health issue you need to speak up and voice those concerns. Ask for a referral to a dietitian who specialises in weight management or to a reputable weight management clinic. I really wish they would have mentioned the great resource that we dietitians can be for all things diet and nutrition.

As you may have guessed, both doctors lost weight during the course of their experiment. I hope that they were the only ones who were surprised by this outcome. Naturally they lost weight; they were both on highly restrictive diets, they were both active males, and this was done over a very short period of time (one month). Imagine trying to sustain a diet with the barest minimum of fat or no carbohydrates for the rest of your life!

Fortunately, the doctors reached a conclusion that I actually agree with! That: “For any diet to work you have to be able to keep it up for the rest of your life.”  As I’ve said many times before: to see sustainable weight loss you need to make sustainable changes.


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Is sugar the “new tobacco”?

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The headline reads “Why are health experts calling sugar the new tobacco?” Because it’s catchy and makes for great headlines, duh!

I know that a lot of people are going to be pissed off with me for not taking up the cause and demonizing sugar. Sorry guys. I agree that most of us consume too much sugar (and too much of anything is a bad thing). I agree that excess sugar can cause cavities. I agree that the vast majority of us like sweet foods. However, I don’t believe that sugar is truly addictive… There is a difference between addiction and desire. Just because rats like oreos and sugar “lights up pleasure centres” in our brains doesn’t make it addictive.

I keep seeing claims that our bodies process calories from white sugar differently than calories from other foods. This makes no sense. The common definition of a calorie (technically a kilocalorie) is: the amount of heat required to raise the temperature of one kilogram of water one degree Celsius (1). There is no way for your body to differentiate between “types” of calories. There is only one type! Your body also can’t distinguish between sucrose in white sugar and sucrose in an apple. It is a chemical compound. It is what it is.

Calling on the food industry to reduce sugar content of foods is a dangerous proposition, in my opinion. Remember when we asked food manufacturers to reduce fat content? They added salt and sugar. Remember when we asked food manufacturers to reduce sodium? Not that much ever came of this. Point being, when they take something out they put something else in to replace it. We now know that fat is not inherently bad for us, nor is sodium, nor is sugar. No one of these things alone is causing obesity. Rather than asking food manufacturers to reduce the sugar content of their foods we should be calling for less heavily processed foods.

Sugar is not the new tobacco. It’s the new scapegoat in the obesity wars.


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Smart Swaps: Not so smart

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Public health is hard. I get it. I was there. It’s hard to come up with ways to improve population health. Nutrition is a particularly difficult area to address. After all, it’s not like smoking where you know that it’s unhealthy and your goal is to convince people to quit (or never start). Nutrition and our relationships with food are complicated. Unfortunately, in most cases, public health campaigns fall flat. I’m afraid that’s going to be the case with the latest Smart Swaps campaign in Britain.

As a few people point out in this news article, money could have been better spent revamping the food system to encourage healthy choices. I’d also like to suggest core curriculum for students so that food skills can be learned young and shared with the entire family.

Beyond the issues raised in the article (i.e. that resources could have been better used elsewhere) I have a bit of an issue with the smart swaps included in the campaign. They seem to be predominantly focussed on calories and weight loss. Yes, there’s swapping sugary cereal to unsweetened cereal, and swapping  sugar sweetened beverages to unsweetened beverages. Not bad swaps. But how about swapping whole milk to low-fat milk, and then swapping that for skimmed milk?  Or swapping butter to lower-fat butter or spreads and cheese to reduced-fat cheese? Yes, that will save you calories but that doesn’t necessarily mean you’re making healthier choices. Fat is not the enemy. Too much of anything is the enemy. Too much highly processed convenience food is the enemy. Not cooking (using minimally processed ingredients) is the enemy. These simple swaps are too simplistic to address the growing problem of obesity and malnutrition.