While there are lots of different diets out there - keto, low carb, low fat, etc. - there is no clear consensus on which diet leads to weight loss or are the best for your health. However, we do have good evidence that one particular category of foods leads to higher rates of heart disease and higher weight.

An interesting study published in the journal Cell Metabolism found that people eat about 500 more calories a day when eating an ultra-processed food diet when compared to eating an unprocessed diet.

In the study, participants were divided into two groups - one that ate a diet of ultra-processed foods for two weeks and another that ate an unprocessed food diet for two weeks. Those eating the ultra-processed diet gained 0.9 kg (2 pounds) while the participants eating the unprocessed diet lost 0.9 kg (2 pounds). The extra calories in the ultra-processed diet group came from extra carbohydrates and fat.

What type of foods are considered ultra-processed? Foods that are more likely to be packaged in a factory. Examples include breakfast cereals, muffins, white bread, flavoured yogurts, granola bars, breakfast sausages, potato chips, canned foods, chicken nuggets, hot dogs, cookies, cold cuts, frozen dinners, fruit juices and diet drinks.

What’s considered unprocessed? Foods that you might have found two hundred years ago. Examples include unsweetened fruits and vegetables, unflavoured Greek yogurt, eggs, oatmeal, grilled chicken, fish, beef, hummus, eggs, whole grains, nuts and seeds.

I’ve always joked that I would easily be my high school weight if I only ate healthy foods all the time because they just doesn’t taste as good. It turns out I may be wrong. According to this study, the participants in both groups rated the food to be equally good tasting, which I have to admit was initially surprising. But take a look at the pictures in the New York Times article and you’ll see that the unprocessed food looks delicious.

One of the biggest differences between the two groups was the speed of eating. Participants eating ultra-processed food tended to eat 17 more calories per minute than the participants eating unprocessed food. This may be because ultra-processed foods contain less fiber and are easier to chew, allowing people to eat more before feeling full. They are also more calorie dense than unprocessed foods.

What I found especially fascinating is that the unprocessed diet group had a significantly higher level of PYY, a hormone that decreases appetite and significantly lower levels of ghrelin, a hormone that increases appetite. In other words unprocessed foods seem to cause fullness before ultra-processed foods.

So what does this mean in the real world? In order to feel more full and either keep from gaining weight or to lose weight, we need to eat more unprocessed foods which are higher in fiber but lower in carbohydrates and fat. Most importantly, they are not necessarily less tasty.

Want to learn more? Read the entire New York Times article here: https://www.nytimes.com/2019/05/16/well/eat/why-eating-processed-foods-might-make-you-fat.html