How to Gain 2 Pounds in 2 Weeks

William T. Basco, Jr, MD, MS


September 26, 2019

There are a whole lot of ways to diet, and many an overweight person has tried them all. Low-fat, low-carb, high-fat, liquid, vegan, paleo, raw—the variations seem to be endless.

One common feature is the recommendation to avoid ultra-processed foods. You know what they are; inexpensive, convenient, ubiquitous, and with long shelf lives. They're high in sugars, calories, and fat. They also may not produce the same gut-to-brain signaling that less processed foods do, and that lack of signaling prevents feelings of satiety. These foods are designed to be overeaten. When manufacturers claim "bet you can't eat just one," they mean it.

While causality cannot be proven, the parallel trajectory is clear. The rise in obesity and complications such as type 2 diabetes have paralleled the increased consumption of ultra-processed foods worldwide.

A recent small randomized crossover study admitted 10 male and 10 female adults to an inpatient clinical research unit at the National Institutes of Health. The study sought to compare the effects of an unprocessed diet versus those of an ultra-processed diet in individuals in a strictly controlled environment. Each of the study participants was randomly assigned to one of the two diet approaches for the first 2 weeks, followed by an immediate switch to the other diet. All were offered three meals per day, given 60 minutes in which to eat them, and instructed to eat as much as they wanted. Both groups were provided with snacks that were appropriate for the diet to which they were assigned.

It was difficult to match the diets for calories, fat, fiber, sugar, and macronutrients, despite attempts to do so. For example, added sugar was much greater in the ultra-processed diet, as was the amount of insoluble fiber and saturated fat.

There were several interesting findings. During the 2 weeks that participants were assigned to the ultra-processed diet, they consumed, on average, a whopping 508 additional calories per day, mostly from fat and carbohydrates. This difference was not affected by gender, baseline BMI, or the order of assignment in the study. The mean daily sodium intake while on the ultra-processed diet was also notable, averaging an extra 1.2 g per day.

Self-reported satisfaction with the taste and quality of the two meal approaches was not different, nor was report of appetite, suggesting that the two diets were equally appealing.

The average weight gain during the 2-week period that the participants were on the ultra-processed diet was 0.9 kg (about 2 lb). The 2 weeks on the comparison diet yielded, on average, a weight loss of 0.9 kg.

Finally, and sadly, the weekly cost of the ultra-processed meals was estimated to be $106. The comparison diet cost 50% more than that.


I typically identify studies to discuss in this series by perusing the pediatric literature, but I heard about this study on the radio and was instantly intrigued. I found the differences shown over a relatively short time span to be truly amazing.

The crossover design, whereby each subject serves as his or her own control, is a powerful one, especially when working with a small number of participants.

I am usually careful to caution against overextrapolation of study findings, as generalization to other populations or situations may be inappropriate. However, there's nothing in the study that would support use of an ultra-processed diet in a developed country—yet another study offering strong evidence that can be used to encourage parents and children to avoid this diet.

This is one area where I am not sure I would wait for confirmation of these results in studies involving children. The ethical conundrum posed by a randomized trial that assigned children to a less healthy diet is obvious.

The greater cost of "higher-quality" foods remains a very real sticking point, but it is one that developed countries must solve. A number of strategies have been tried and demonstrated some success. A recent study found that a "snack tax"—making lower-quality foods more expensive—can have a real effect on reducing caloric intake and obesity. Legislation requiring more healthy options for school lunches is another potential avenue to target this issue. The Healthy, Hunger-Free Kids Act, first passed in 2010, required that more whole grains, fruits, and vegetables and low- or no-fat dairy products be provided to the 30 million US children who receive lunch at school. Federal food programs are another important source of food for kids and provide an additional avenue to tackle cost. We have to find the political will to try.

William T. Basco, Jr, MD, MS, is a professor of pediatrics at the Medical University of South Carolina and director of the Division of General Pediatrics. He is an active health services researcher and has published more than 60 manuscripts in the peer-reviewed literature.

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