Eating less processed foods and more whole foods has been a kingpin in nutritional advice for ages. We may get tired of hearing about it, but a clinical study produced by the National Institute for Health dated for August of 2019 has given us more reasons to take notice of the benefits of eating minimally processed, whole foods.
Kevin Hall, a global obesity expert, led the research which involved 20 healthy adults over a 28- day time-period. The test subjects lived in a clinical setting and were exposed only to foods that were provided to them by the researchers. They were divided into 2 groups, either a minimally processed diet or an ultra-processed diet, but their intakes, calories, and portions were left up to the individual.
The researchers manipulated the diets to keep them as similar in relative percentages of carbohydrates, proteins, fats, sugars, fibers, sodium, and nutrients. They added soluble fiber to drinks for those subjects on the ultra-processed diet and gave more fresh fruit to the minimally processed group to make the fiber and sugar consumption as similar as possible between the two groups. Normally, a highly processed diet lacks fiber, and a whole foods diet lacks the extra, hidden sugars found in processed foods.
The food served on the ultra-processed group contained convenience foods, like canned soups and rice-in-a-pouch, so it wasn’t all the typical chips, sodas, cookies, and those foods we tend to think of us processed. The thing all the processed foods has in common was that it was “formulated from mostly industrial ingredients and contained little or no intact food.”
On the ultra-processed diet, the subjects consumed 500 calories more per day than those on the minimally processed diet, resulting in a weight gain of 2 pounds in 14 days. For the last 14 days of the experiment, the processed-diet subjects were then fed the minimally processed diet, and they lost those 2 pounds they had gained in the following 14 days.
Why is it so easy to gain weight with processed foods? Hall believes that it is due to the fact that processed foods are softer and easier to chew, resulting in eating more before the stomach can signal the brain that it’s full (a process that takes a full 20 minutes for the signal to occur).
The appetite-reducing hormone PYY is higher in people who eat unprocessed foods, and the hunger-hormone ghrelin is respectively lower. Unprocessed foods provide more nutrients, satiety, and better hormone control.
Try to focus on eating whole foods that are as close to their natural form as possible—apples rather than apple juice, fresh chicken rather than deli chicken, whole grains rather than bleached white bread—to see the benefits of eating whole foods. Bookmark your favorite recipes in this whole foods cookbook to make it easy to stay on track.
References
- Hall, Kevin D, et al. “Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.” Cell Metabolism, vol. 30, 2 July 2019, pp. 67–77., https://www.cell.com/cell-metabolism/pdf/S1550-4131(19)30248-7.pdf.
