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The Link Between Obesity and Diets High in Processed Foods - A Tightly Controlled Lab Study

Kimberly England's picture
Hamburger Processed Food

We’ve known for some time the obesity epidemic has been an issue and connected to highly proliferate processed foods, but now the results are in. Stunningly, it isn’t just the obesity in a person impacted.


On Thursday, May 16, 2019, a study was published online by Cell Metabolism where scientists, in a tightly controlled lab study found that volunteers in a controlled group for two weeks who ate ultra-processed foods, gained more calories and a few more pounds when on a highly processed diet versus a high diet rich in whole foods. Lucia L. Kaiser, PhD, community nutrition specialist in the Department of Nutrition at the University of California, Davis says, “If you’re trying to eat a healthier diet, relying on more whole foods is a great place to start “.

The study also showed processed foods pack more sugar and fat. Furthermore, the frequent use of processed foods increased the urge to eat faster.

In the study, both diets offered the same daily calories, similar amounts of total sugar, fat carbohydrates and fiber. During the two weeks, the volunteer group, eating mostly processed foods, chose to eat more on average of an extra 500 calories per day. They gained a few pounds on the ultra-processed food but lost that much during their two weeks on a minimal processed diet.

20 inpatient adults received ultra-processed and unprocessed diets for 14 days each;
Diets were matched for presented calories, sugar, fat, fiber and macronutrients;
Ad libitum intake was ∼ 500 kcal/day more on the ultra-processed versus unprocessed diet;
Body weight changes were highly correlated with diet differences in energy intake.

They investigated whether ultra-processed foods affect energy intake in 20 weight-stable adults, aged (mean ± SE) 31.2 ± 1.6 years and BMI = 27 ± 1.5 kg/m2. Subjects were admitted to the NIH Clinical Center and randomized to receive either ultra-processed or unprocessed diets for 2 weeks immediately followed by the alternate diet for 2 weeks. Meals were designed to be matched for presented calories, energy density, macronutrients, sugar, sodium, and fiber. Subjects were instructed to consume as much or as little as desired. Energy intake was greater during the ultra-processed diet (508 ± 106 kcal/day; p = 0.0001), with increased consumption of carbohydrate (280 ± 54 kcal/day; p

Both insulin secretion measured by 24-h urinary C-peptide excretion (38.9 ± 2.8 nmol/day versus 30.9 ± 2.8 nmol/day; p = 0.052) and average daily glucose levels measured by continuous glucose monitoring (CGM) (99.1 ± 1.3 mg/dL versus 96.0 ± 1.3 mg/dL; p = 0.10) tended to be slightly higher compared to the unprocessed diet.

Changes in body energy stores were calculated using the repeated body composition measurements and were found to be increasing by 307 ± 85 kcal/day (p = 0.002) during the ultra-processed diet and decreasing by 220 ± 88 kcal/day (p = 0.02) during the unprocessed diet. Energy balance calculated as energy intake minus expenditure by DLW was not significantly different from the calculated rate of change of body energy stores during the ultra-processed diet (111 ± 111 kcal/day; p = 0.33) but was 382 ± 92 kcal/day (p = 0.0007) greater during the unprocessed diet.

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Even though the study was only conducted in a 14-day window, it’s easy to see that the possibility of severe health risk can be achieved over a longer period of time. The health dangers range from insulin, cholesterol, oxidative stress, heart disease, vascular disease and more.

It’s no surprise that a lot of folks are extremely busy and are in that “hit and go” quick eats mentality without thinking through long term consequences for our health. Just to keep things simple, we first need to know “What is processed food”? Let’s look at how The American Heart Association defines processed foods as seen below.

What is processed food?
Most foods are processed – changed, prepared or packaged – in some way before we eat them. They fall somewhere on a spectrum from minimally processed (like salad mix, bagged dry beans, roasted nuts or frozen fruits and vegetables) to what some nutrition experts refer to as highly or ultra-processed (like ready-to-eat meals and snack foods).

Some processed foods have ingredients added, like sweeteners, oils, colors and preservatives. Some are fortified to add nutrients like fiber, calcium or vitamin D. Some are simply prepped for convenience (washed or chopped) or packaged to last longer. Processes such as pasteurizing milk, canning fruits and vegetables, and vacuum packing meats help prevent spoilage and increase food safety. Even foods labeled “natural” or “organic” can be processed.

If you eat a lot of highly processed foods, you risk getting too much sodium, added sugars and unhealthy fats. Highly processed foods contribute almost 60% of calories and 90% of added sugars in the American diet, according to a 2016 research study.

What can you do if want to eat healthier? While it’s tempting to throw all “processed food” under the bus, the reality is you can’t avoid it entirely… nor should you! The key is knowing how to identify healthier processed foods and make smart choices in the grocery store and restaurants.

Now that you see how the convenience of ultra-processed food does more damage to the body, will you consider dietary changes? Making healthier food choices can help one live a healthier, happier, more energetic life. Let go of some of the high processed "food munchies and quick fixes" for a time to give your body a chance to heal. Slow down your chewing process and enjoy a fantastic fresh or organic meal for a change.

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