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What Happens When You Eat Ultraprocessed Food for a Month?

It likely comes as no surprise that eating a diet filled with ultraprocessed foods is unhealthy. Research has demonstrated ultraprocessed foods can increase your caloric intake and weight gain.1,2

Data3 gathered from 2009 to 2010 from the National Health and Nutrition Examination Survey showed ultraprocessed foods made up 57.9% of the energy intake of Americans and sugar contributed 89.7% of the energy intake.

By 2019, a study published in the journal Nutrients4 found 71% of packaged products in the grocery store were ultraprocessed. Researchers from Northwestern Medicine estimated nearly 80% of the total calories consumed by Americans is from store-bought food and beverages.5

The researchers also compared the food supply in the U.S. against other western countries like Australia, finding packaged foods Americans were eating had higher median amounts of sugar and salt. These foods contribute to the rising level of obesity across the world.

The World Health Organization reported worldwide obesity tripled since 1975.6The rate of overweight and obesity are rising rapidly in the U.S. as well. Data gathered from 1999 to 2000 and then again from 2017 to 2018 show the prevalence of obesity rose from 30.5% to 42.4%.7 During the same periods, the prevalence of severe obesity rose from 4.7% to 9.2%.

The Centers for Disease Control and Prevention reported that from 2017 to 2018, the prevalence of obesity was 19.3% in children and adolescents aged 2 to 19 years.8 However, as data have demonstrated and one BBC reporter illustrated, what you eat is a key factor in your health.9

BBC Reporter Eats Only Ultraprocessed Food for One Month

BBC television presenter Dr. Chris van Tulleken was interested in what would happen if he changed his diet for just one month. Tulleken, presenter of "What Are We Feeding our Kids?" was curious about how ultraprocessed foods affect our bodies. The BBC reports that in the U.K, as in the U.S., over half the energy from food in the average diet comes from ultraprocessed products.10

Over one month, 42-year-old Tulleken increased his daily intake of ultraprocessed products from 30% to 80%, mimicking how 20% of the U.K. population eats.11 At the end of four weeks, Tulleken experienced a myriad of changes to his health, including:

Poor sleep

Heartburn

Anxiety

Sluggishness

Low libido

Unhappy feelings

Hemorrhoids (from constipation)

Weight gain of 7 kilograms (15.4 pounds)

"I felt ten years older, but I didn't realize it was all [because of] the food until I stopped eating the diet," Tulleken told the BBC. This is telling, since the physician purposefully changed his diet and yet did not recognize feeling 10 years older in one month was associated with the food he was eating.

How much more difficult might it be to convince others that the way they are feeling is related to the chemicals they are consuming? At the rate he gained weight, he believed if he'd continued for six months, he would have gained 6 stone (84 pounds).

These were the health effects Tulleken could identify without testing. He also underwent several measurements of health biomarkers, which demonstrated significant changes from only four weeks of eating ultraprocessed foods.12

Brain scans showed that the diet had created new links in his brain from areas responsible for reward to areas that drive automatic and repetitive behavior. This is a similar response to taking classically addictive substances, such as tobacco, alcohol and drugs.

The brain changes that occurred in the short time that Tulleken had consumed high amounts of processed products were not permanent. However, it isn't possible to make the same assumption if the diet is followed for months or years. Additionally, Tulleken points out "if it can do that in four weeks to my 42-year-old brain, what is it doing to the fragile developing brains of our children?"

You Eat More When You Eat Ultraprocessed Foods

Tulleken also discovered he consumed about 500 calories more each day than he had before he began the ultraprocessed diet. This was consistent with a study13 from the National Institutes of Health conducted by Kevin Hall, Ph.D., senior investigator at the NIH Intramural Research Program. In Hall's research he compared two diets that were matched for macronutrients, sugar, salt and fiber content.

One diet was about 80% ultraprocessed products and the other was an unprocessed diet. The group consumed the ultraprocessed diet for two weeks and then was switched to the unprocessed diet while admitted and monitored at the NIH Clinical Center.

The participants were encouraged to eat as much or as little as they wanted. The scientists found that when the participants ate the ultraprocessed diet they consumed more carbohydrates, but not protein. During the two-week intervention, participants gained approximately 0.9 kilograms (2 pounds) while eating the ultraprocessed diet and lost the same amount eating the unprocessed diet.14

The BBC reports Hall’s team also measured hormonal biomarkers responsible for feelings of hunger and satiety.15 As you might expect, the hormone responsible for hunger (ghrelin) increased and that responsible for feeling full (leptin) decreased while participants were eating the ultraprocessed products.

These results were consistent with Tulleken’s experience, as his ghrelin level increased by 30% during the four weeks that he ate ultraprocessed products. In that month he found himself craving food more often and eating more quickly, which likely contributed to eating more food. What is classified as an ultraprocessed food may surprise you.

NOVA16 classifies food categories according to the extent and purpose of processing, rather than the nutrients found in the food. NOVA categories are recognized as a valid tool for nutrition and public health research and are used in reports from the United Nations and Pan American Health Organization.17

According to NOVA,18 ultraprocessed food and beverages have industrial formulations, typically with five or more of these types of ingredients. Below is a list that is not all inclusive but does offer insight into the types of foods that are considered ultraprocessed.19 As you can see, some are products that are touted as a healthy food choice, such as breakfast cereals, energy bars and fruit yogurt.

Ice cream

Chocolate

Candy

Pastries

Cakes and cake mixes

Breakfast cereals

Cookies

Fruit yogurt

Fruit drinks

Energy bars

Cocoa drinks

Infant formulas

Energy drinks

Instant sauces

Ready-to-heat products

Powdered or packaged instant soups, noodles and desserts

Mass-produced bread and buns

Margarines and spreads