bite my words

Dispelling nutrition myths, ranting, and occasionally, raving


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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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More on fat tax

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Recent research showed that a combination of factors was best at discouraging purchasing of “junk” foods. It also showed that, on their own, cheaper healthy options, anti-obesity advertising, and healthy food advertising were ineffective at dissuading “customers” from purchasing the junk food. However, increasing the price of the “junk” by 20% was persuasion enough for customers to select the healthier options.

While an interesting result, there are a number of problems with applying these findings in the real world. The research was done with participants in a laboratory. Thus, their economical means and purchasing behaviours may not have been representative of how they would act in “reality”. Also, were participants representative of the population? I worry the most about the impact of jacking up prices on “junk” food on those who are experiencing food insecurity. Increasing the cost of these foods may cause more harm than good.

In addition, as mentioned in the article we’ve already seen the failure of the “fat tax” in Denmark. Why would we think that increasing the price of “junk” food would be any more effective in North America? And who will decide what foods are healthy and what foods are unhealthy and deserving of taxation. I’ve seen granola bars that were not permitted under school nutrition policies that (in my opinion) were healthier than those that were permitted. The ones that were permitted contained chocolate chips. The ones that weren’t contained almonds, causing the fat content to be too high to meet criteria! Research is always evolving and even within the dietetic world there isn’t consensus on some matters. Some dietitians would rule out butter in favour of margarine. Some would be okay with added sugars, while others would eschew them. Most would say that all foods are okay, with some being everyday foods and others being occasional foods.

Also, what would happen with the increased revenue from “junk” foods? Would it go to the food industry? Would it go to the government? Or would it go to subsidise vegetables and fruits or create community food initiatives?

Yes, this research provides some insight into human behaviour. However, I’m not sure that it’s all that useful of a weapon in the war against obesity.


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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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Fast food won’t make you fat?

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Guess what?! Fast food isn’t making people obese! Rejoice! Eat Big Macs! At least that’s what the latest study on fast food would have you believe. The researchers found that fast food consumption wasn’t the cause of obesity. Instead, it was the overall dietary pattern. No matter that the fast food was part of the overall dietary pattern. No matter that children who regularly consumed fast food were, in fact, more likely to be overweight or obese than children who did not consume fast food. And, no matter that weight isn’t the be all and end all when it comes to health. Even if children who are regularly consuming fast food aren’t overweight (which actually wasn’t what this study found) that doesn’t mean that they’re healthy. It’s quite likely that they’re lacking in essential nutrients.

In addition to the issues mentioned above, it’s also important to note that the study looked at data from the NHANES (National Health and Nutrition Examination Survey). Due to the flaws in dietary recall, it’s difficult to put too much credence in these results. It’s also important to recognise that anyone working in obesity and/or nutrition will tell you that there is no one single culprit when it comes to obesity. Just because fast food is not the sole cause of overweight and obesity doesn’t mean that it’s not a contributing factor. It’s one component in our broken food system.

 


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Unsatisfied with Satisfries

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I’m sure you’ve heard about Burger King’s new “Satisfries” by now. They’ve been all over the papers and my twitterfeed and chances are, two days later, I’m the last dietitian to blog about them. But even if the topic’s been blogged to death how can I not address it?

My first thought was “I don’t know how I feel about these fries”. At 20% fewer calories and 30% less fat than BK’s standard fries they do provide a slightly less unhealthy option for fry-lovers. As many of us dietitians like to suggest making small initial changes (e.g. milk instead of cream in coffee) to help clients with weight loss goals I thought, “well, maybe these have a place”. But then I thought about it some more…

I said that the Satisfries are slightly less  unhealthy because, despite what BK would like you to believe, they are still not actually healthy. They are still deep-fried potatoes. How did they reduce the fat and calories? Apparently they changed the proportions of the breading they use on the potatoes so that they absorb less of the oil in the deep-fryer. Awesome. Because we all love secret breading recipes on our fries, right? They still don’t have much in the way of nutrients other than calories from simple carbohydrates and fat. They have no vitamins to speak of and the only real mineral is about a third of your daily sodium.

I also started having visions of the fat-free frenzy in the 80s, and the current sugar-free and gluten-free frenzies. Did the reduction of any of these nutrients in the food supply have any effect on the obesity rates? Is our population any healthier as a result of these initiatives? Nope and nope. All it is, is clever marketing by companies to have us feel better about the crappy food they’re peddling. Odds are, as with the other initiatives, if one orders these Satisfries they’ll end-up over-indulging in something else and undermine  their efforts to eat better. The Satisfries will sit on the tray, just like the diet pop, with the 1, 250 calories Triple Whopper with Cheese because, after all,  they’re having the healthy fries. As far as efforts to curb obesity rates go, reformulating processed food is going to do little or nothing. What we really need is a complete overhaul of the current food and education systems, as well as our physical environment.

My final issue with these fries is the implication of the name. What exactly about a french fry with fewer calories and less fat than a regular fry makes them satisfying? Wouldn’t they be less satisfying than regular fries?

French fries, unless they are oven-baked from whole potatoes with olive oil and spices, are undeserving of a health halo regardless of how you slice (or bread) them.

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