Thinking Nutrition

Focussing on eating healthier is better than trying to eat less

March 22, 2022 Dr Tim Crowe Episode 95
Thinking Nutrition
Focussing on eating healthier is better than trying to eat less
Show Notes Transcript

With no end of diets to choose from, it is clear they collectively make little long-term impact on body weight with most people regaining any weight lost within months. So, rather than putting the focus on dieting to lose weight, how much impact could a change in mindset to concentrate on eating healthier have instead? Well, in an interesting twist to this question, a research study designed to educate people on portion sizes, actually found that people ate more food. But the catch was that it was healthier food options they were choosing, with the flow-on benefit of them eating fewer kilojoules overall.

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With no end of diets to choose from, it is clear they collectively make little long-term impact on body weight with most people regaining any weight lost within months. So, rather than putting the focus on dieting to lose weight, how much impact could a change in mindset to concentrate on eating healthier have instead? Well, in an interesting twist to this question, a research study designed to educate people on portion sizes, actually found that people ate more food. But the catch was that it was healthier food options they were choosing, with the flow-on benefit of them eating fewer kilojoules overall.

There has been a trend over recent decades for food to be served in larger portion sizes. This portion growth applies equally to food purchased out of the home and food served at home. As portion sizes go up, people can easily eat more than they intended. And this effect of a change in norms for just what a normal portion is has the name of portion distortion. And you see this effect of a greater likelihood to eat more food as the serving size, packaging size or tableware size used grows.

Of course, having an awareness of this can help in combatting our innate tendency to overeat. Someone could consider making a conscious choice to self-serve smaller portions of kilojoule dense foods such as desserts, drinks and fatty foods. Or to eat food from smaller bowls, plates, or cups. Maybe even when shopping, to be wary of the ‘two for one’ or ’30 percent more’ label promotions on food, especially for confectionery and other snack items.

But what happens when you put such ‘portion distortion’ strategies into action? As a way to help address ‘portion creep’, a research team designed a program to help educate a group of people on controlling portion size as part of an ongoing weight loss intervention.

Here’s how the study ran. Three groups of women, some of whom had already completed a one-year weight-loss trial that included portion-control strategies, visited a food lab once a week for four weeks. At each visit, the women were given the same foods to eat, but portion size varied. Each meal they were presented with had a range of foods in it to choose from. And options included high kilojoule dense foods such as chocolate-chip cookies as well as lower kilojoule dense foods such as salads. And I’ll link to the study in the show notes. https://pubmed.ncbi.nlm.nih.gov/29353006 

So, what happened? When larger meal portions were served, the women ate more food which was the expected finding. For example, when the portion size was increased by 75 percent, 27 percent more food by weight was eaten.

Seems like a fail for the experiment as you would expect those that had portion control training to eat less right? Not so fast. Because the food choices on offer differed, then even though more food by weight and volume was eaten by both groups of women, in the women that had already undertaken portion control training, they ate more of the lower kilojoule-dense foods and less of the higher kilojoule-dense food. That meant compared to women that had no portion control training, even though the volume of food eaten was the same between the groups of women, the overall kilojoule intake was lower because of choosing more of the lower kilojoule-dense options.

If you look at foods and rank them based on energy density, which is the number of kilojoules per gram, you are going to see an over-representation of healthier foods like fruits, vegetables and more minimally processed foods at the lower end of the spectrum – foods with lots of fibre, water and not a lot of added ingredients. At the other end of the spectrum, foods with a high energy density will be over-represented with fat and sugar dense convenience foods – most of these are not so much a healthy choice.

So, what’s the take-home message from this research study? First, I need to acknowledge that this is just a single study so we can’t put full weight on the findings. But here’s my take: choosing to eat greater amounts of healthier lower kilojoule-dense foods such as fruits and vegetables is a more effective and sustainable approach to eating than just trying to resist food or control portions of higher kilojoule foods or calorie count on yet another diet for that matter. It fits in with a nice mantra that if you get the foods right, it will take care of a lot of the issues to do with nutrient needs and your overall health.

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.

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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.