A recent study, summarized here, conducted by the National Institutes of Health (NIH) found that individuals ate more food and calories when eating highly processed food as opposed to minimally processed food. The study was small – just 20 individuals – 10 men and 10 women – but they were fed in a clinic for one month. Half of the time they ate minimally processed food, and half of the time they ate highly processed food.
The meals were designed to have the same breakdown of macronutrients (fat, protein, and carbohydrate), however participants could eat as much as they wanted. In other words, they were given a tray of food as one might in a hospital. They couldn’t eat more than what was on the tray (along with snacks they were allowed daily), but they didn’t have to eat it all. The available calories were really very high, so no one was going hungry.
When eating highly processed foods, individuals consumed about 500 calories more per day than those eating minimally processed foods. They also consumed their food more quickly.
There are pictures available of their meals. You can get a sense of how much of a higher volume of food you can eat when eating minimally processed foods.
It doesn’t surprise me that people eat more food when they eat highly processed food than when eating real whole foods. What does surprise me is that this hasn’t been studied until recently. But it’s consistent with a lag between anecdotal evidence regarding proper nutrition, and scientifically proven data to back it up. This is due to timing, funding, the power of the food industry lobby, and many other factors I’m sure.
I think this is helpful information not just because it demonstrates that whole real food can help us naturally regulate how much we eat, but also because it helps us to recognize that processed foods can be addictive and cause us to eat too much. Picture sitting down with a bag of tortilla chips vs. a bag of raw almonds. The almonds may be denser in calories per ounce, but your brain will register satiety much quicker than with the tortilla chips. Even leaving out the discussion about getting nutrients from whole food that’s absent in highly-processed food, you can see how you would just consume too much.
The correlation wasn’t just mental. The study found that on the minimally processed diet, participants had higher levels of PYY, an appetite suppressing hormone, and lower levels of ghrelin, the hunger hormone. Other health markers also improved on the minimally processed diet, including a lower fasting glucose level and lower insulin levels.
If this topic interests you, I wrote previously about the food manufacturing process designed to find our bliss point and get us to eat more. If you are ready to switch to a more whole-foods-based diet, here are some tips I have provided about what the switch means and what to be on the look out for.