Can you eat junk food and be healthy?

Proportions matter, and when half our daily calories come from junk food our health is on the line

There’s a place for everything that’s tasty and enjoyable to eat in a healthy diet, that’s what I believe. I can also support this declaration with plenty of scientific literature showing that long lived communities as well as large cohorts in studies maintained health and avoided excessive weight gain without abstaining from dessert – traditional diets don’t declare abstinence from sweets or fried foods.

It’s the proportions that matter. If 90 percent of what you eat is nutritious you can play with the rest. If 80 percent of your days are reasonably active, hibernating couch-potato style on a lazy day will do no harm.

But here’s the problem: Our proportions have turned upside down, completely. 

Junk all around

A new study in the Journal of Nutrition assesses the amounts of junk food in the American diet using two nationally representative data sources, including more than 10,000 people.

What is junk food? The academic literature struggles with this question. Salty snacks, candy and soda are the hallmark representatives, but there are many other products – such as bakery products, sweet breakfast cereals, fast-food and processed meats – that should be in the eat-less/junk category.

This study uses the 2016 Chilean law for food labeling and advertising definitions of junk food. This law identifies foods with high caloric density, high added saturated fat, sugar and salt, and imposes marketing and advertising regulations upon them, including warnings on the front label and a ban from sales in schools.

And the results: Between 2015-2018 almost half of daily calories US adults consumed were derived from junk food. Sugary drinks composed almost half of the sugar from these junk food.

This study paints a picture concordant with another study in kids, that finds that 56 percent of the calories US kids consume come from junk food.

This current study also found that there are disparities in junk food intake among ethnic groups, with non-Hispanic black adults consuming more junk food, and with the highest income group consuming the lowest amount of sugary drinks.

You are what you eat 

Obesity, type 2 diabetes, hypertension and many other chronic conditions are nutrition associated diseases – they could be avoided or ameliorated by a healthy diet and lifestyle.

We know that the more junk food in a society’s diet the greater the obesity rates. A recent large prospective study found that a 10 percent increase in ultra-processed food is associated with a 10 percent increased risk in overall cancer and breast cancer rates. A study following 12,000 Americans with no underlying illnesses for more than two decades found a 30 percent higher risk of dying in the group consuming more junk food.

If people just replaced junk foods they’d likely gain less weight and perhaps shed some.

A study in the BMJ simulated what would happen if kids reduced their junk food intake, and estimated that childhood obesity rates would drop from 20 to 11 percent, and there’s be 16 percent fewer overweight kids. This simulation extrapolates from a randomized controlled trial in which people alternated between highly processed and less processed diets which were matched for total calories, energy density, carbs, protein and fat, fiber, sugars and salt and instructed to eat as much as they wanted. People on a junk food diet consumed on average an additional 500 calories daily than they did on an unprocessed diet.

You know it when you see it

As to the definition of junk food, no system of categorizing food will be perfect, and we can debate whether warnings on the front of the package are the best way to reduce the intake of what’s inside.

Although academics may struggle with the definition of junk food, for the most part, we know junk food when we see it. The problem is that we see so much junk that it's normalized. Mainstream supermarket’s shelves sell more highly processed and junk food than wholesome ones, pharmacy and convenience store shelves stock almost nothing but junk, and advertising efforts focus almost only on these products. 

It’s really no surprise that half of what Americans eat is junk when so much of what’s offered to them in reality and digitally is highly processed sugary drinks, candy, fast food, mass produced chips, highly sweetened cereals and cured meats.

Dr. Ayala