WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
In recent decades, the food system responsible for feeding millions of people has drastically changed, impacting food safety and human health. The manufacturing of vegetable oil1 and changes in how your cereals,2 salads3 and meats4 are grown, processed and adulterated before finally reaching your plate, have dramatically altered the overall nutrition of most people's diets.
Americans spend 57.9% of their food budget on ultraprocessed foods,5 which means more than half of what the average American eats in any given day are foods that may be purchased at the local gas station or convenience store. These foods also account for 89.7% of added sugars in the diet.6
Data from a nationally representative food survey was used in a 2016 study,7 which found 70.4% of calories came from processed foods while less than 1% (0.7) came from vegetables. This change in eating habits over time may be a result of the Push hypothesis, described by Kevin Hall, Ph.D., from the National Institute of Diabetes and Digestive and Kidney Diseases.8
He describes this as a combination of factors pushing calories into the food system and subsequently changing the way we eat. These cheap convenience foods are contributing to the obesity epidemic.9 Hall and his team recently published a rigorous study10 in the journal Cell Metabolism, demonstrating the effect ultraprocessed diets have on excess calorie intake and weight gain.
Rigorous Study Demonstrates Ultraprocessed Food Leads to Weight Gain
A small scale, but rigorous, randomized and carefully controlled study was performed by the National Institutes of Health to analyze if those eating ultraprocessed foods ate more calories and gained more weight. The researchers recruited 20 healthy adult volunteers — 10 women and 10 men in their 30s. The group were admitted for four continuous weeks into the NIH Clinical Center.11
The participants were randomized into two groups who received an ultraprocessed or unprocessed diet for the first two weeks and were immediately switched to the alternate diet for the next two weeks.
The researchers offered the participants three meals a day, matched for calories, macronutrients, sugar, sodium and fiber at an amount equivalent to double their estimated requirement for weight maintenance. The participants were encouraged to eat as much as they wanted.
During these four weeks, the researchers measured energy intake, weight changes and took metabolic measurements.12 As noted by the NIH,13 observational studies in the past have shown an association between diets high in processed foods and health problems.
In this study,14 the researchers were intent on demonstrating whether processed foods were a problem on their own or whether individuals eating processed food already had health problems that were unrelated to diet. The data showed an average increase of 459 calories per day when eating ultraprocessed foods compared to the unprocessed diet.
Increased energy intake occurred over breakfast and lunch, with no significant increases in calories at dinner in those eating an ultraprocessed diet. During the study, the researchers also found those eating the ultraprocessed meals ate significantly faster than those eating the unprocessed foods, which may have led to higher energy intake.
They hypothesized the orosensory properties of the ultraprocessed foods may have increased the eating rate and delayed satiety signaling.15 This may have resulted in a greater overall calorie intake. While on the ultraprocessed diet, people gained an average of 1.98 pounds over two weeks, and while on the unprocessed diet lost the same amount.16
Dr. Dariush Mozaffarian, cardiologist and dean of Tufts University Friedman School of Nutrition Science and Policy, says,17 "Putting people in a controlled setting and giving them their food lets you really understand biologically what's going on, and the differences are striking."
What Are Ultraprocessed Foods?
The researchers defined ultraprocessed foods using the NOVA classification system18,19 that considers food with ingredients predominantly found in manufacturing as ultraprocessed, such as high fructose corn syrup, flavoring agents and emulsifiers.
The New York Times20 published examples of processed meals the participants may have received, such as Cheerios, Chef Boyardee ravioli, diet lemonade and Otis Spunkmeyer cookies or blueberry muffins, and chicken salad with canned chicken and Hellman's mayonnaise. Barry Popkin, nutrition professor at the University of North Carolina, who was not involved in the current study, commented:21
"The difference in weight gain for one [group] and weight loss for the other during these two periods is phenomenal. We haven't seen anything like this. We should try to eat as much real food as we can. That can be plant food. It can be animal food. It can be [unprocessed] beef, pork, chicken, fish or vegetables and fruits. And one has to be very careful once one begins to go into other kinds of food."
While every attempt was made to completely match nutritional parameters, the researchers found ultraprocessed versus unprocessed meals differed markedly in the total amount of added sugar, as well as in insoluble fiber and saturated to total fat.
Not surprisingly, they also found the ratio of omega-6 to omega-3 fats was a whopping 11-to-1 in ultraprocessed foods, but only 5-to-1 in unprocessed foods (the 5-to-1 is near ideal and is what a balanced omega-6 to omega-3 diet should like).
Link Between High Levels of Omega-6 and Obesity
Omega-3 fats are essential polyunsaturated fats your body requires for a variety of functions, including muscle activity, cognition and heart health. While omega-3 fats are available in some plants and marine animals, it is the marine-based omega-3 fats docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) that are crucial for optimal functioning of cells and mitochondria.
DHA appears to be particularly important for your brain22 while EPA is of greater importance for heart health.23 Omega-6 fats are also essential nutrients your body needs for normal growth and development. The difference is omega-6 fats are found easily in many processed foods and in nuts and seeds.24
An overabundance of omega-6 fat increases the risk your body will produce inflammatory chemicals.25 The ideal ratio of omega-3 to omega-6 fats ranges from 1-to-1 to 1-to-5, which is nearly impossible if you're regularly eating processed foods or restaurant fare, as these are loaded with omega-6 from industrial vegetable oils like corn oil and canola oil. In a standard Western diet, the ratio is often 1-to-15 or greater.26
The deficiency in omega-3 fats and abundance of omega-6 may promote the pathogenesis of many diseases, including inflammatory and autoimmune diseases, cardiovascular disease and cancer. Increasing omega-3 consumption may exert a suppressive effect.
For instance, one author writing on the importance of a balanced ratio27 found a ratio of 4-to-1 associated with a 70% decrease in total mortality from cardiovascular disease. A ratio of 2.5-to-1 reduced proliferation of rectal cells in those with colorectal cancer and a ratio of 2-3-to-1 suppressed inflammation in those suffering rheumatoid arthritis.
Multiple studies28,29,30,31 have found a close association between chronic low-grade inflammation, in part triggered by the composition of fatty acids in the diet, and insulin resistance with an increase in the risk for obesity. In other words, the higher levels of omega-6 fats found in ultraprocessed foods increase chronic inflammation and your risk for developing insulin resistance and obesity.
Several Factors May Lead to Overeating Ultraprocessed Foods
The featured study32 in Cell Metabolism also found several factors contributed to overeating ultraprocessed foods. Those eating the ultraprocessed foods had a higher eating rate that may have potentially been affected by the orosensory properties of foods, which were softer, easier to chew and swallow, and may have led to eating more quickly.
Additionally, the researchers found ghrelin,33 a hormone released by the body to trigger hunger, was decreased in those eating the unprocessed diet, compared to their baseline measurements.34 After eating an unprocessed diet the participants' fasting glucose and insulin levels also tended to be lower compared to baseline.
Compared to the unprocessed diet, measurements after eating the ultraprocessed diet were unchanged from the participants' baseline measurements, suggesting the subjects had likely consumed a diet habitually high in ultraprocessed foods. Hall commented:35
"One thing that was kind of intriguing was that some of the hormones that are involved in food intake regulation were quite different between the two diets as compared to baseline."
Obesity May Overtake Tobacco as Top Cause of Cancer
According to the National Cancer Institute,36 tobacco is the leading cause of cancer and the leading cause of death from cancer. Those who smoke, or those who are regularly around secondhand smoke, have an increased risk since the many chemicals in the tobacco damage DNA. Cancers associated with tobacco include:37
Lung |
Mouth | Esophagus |
Larynx |
Bladder | Kidney |
Liver |
Stomach | Pancreas |
Colon |
Rectum | Cervix |
Although smoking has held the No. 1 spot for preventable causes of cancer for decades, it appears obesity is not far behind. According to Dr. Otis Brawley,38 professor of oncology in epidemiology at Johns Hopkins University and former chief medical officer of the American Cancer Society, this which may occur within the next five or 10 years.39
However, it appears many Americans are unaware that some of the leading causes of cancer are controllable, including obesity.40 The International Agency for Research on Cancer41 has identified a link between being overweight or obese and an increased risk for developing certain types of cancers.
Compared to those who are within a normal weight range, those who are obese are also likely to have a recurrence of their cancer with a lower likelihood of survival. Research published in the New England Journal of Medicine42 concluded "Increased body weight was associated with increased death rates for all cancers combined and for cancers at multiple specific sites."
Reuters reports43 the rate of cancer unrelated to obesity declined by 13% between 2005 and 2014, while obesity-related cancers rose by 7%. They also reported the U.S. Center for Disease Control and Prevention released data showing 630,000 people in the U.S. were diagnosed with cancer linked to being overweight or obese in 2014. This accounted for 40% of all cancers in 2014.
As the overall rate for new cancer diagnoses continues to fall, the rates of obesity-related cancers are rising, along with the rates of obesity. A report published in the Journal of the American Medical Association44 found obesity rates rose from 33.7% to 39.6% between 2007 and 2016.
Although the exact association between cancer and carrying excess weight is not fully understood, researchers are focusing on studying visceral fat, as it is metabolically active, secreting proteins that drive insulin levels higher and may spur cellular growth.45
As Ultraprocessed Food Has Become the Norm, so Has Chronic Illness
Rising rates of obesity and reliance on processed and ultraprocessed foods is likely linked to an increasing risk of early death and chronic disease, such as cardiovascular disease,46 Type 2 diabetes47 and arthritis.48 Foods rich in omega-6 fats create chronic inflammation in the body, which has been linked to each of these conditions.
In one study,49 a French team looked at how much of a person's diet was made of ultraprocessed foods and found for each 10% increase, the risk of death rose by 14%. After removing confounding factors such as smoking, obesity and low educational background, the link remained.
In a cross-sectional study50 using data from the National Health and Nutrition Examination Survey of over 9,000 participants, the researchers concluded: "Decreasing the consumption of ultraprocessed foods could be a way of reducing the excessive intake of added sugars in the USA."
Your Diet Is a Key Factor in Health and Longevity
Undoubtedly, there is a serious health epidemic in the U.S., and a majority of it is linked to diet. There are no quick and easy answers. It is crucial to remember what you eat is the foundation on which your health is built and eating a processed food diet is a recipe for long-term disaster.
If you have access to real food, it is important to take the time to learn to cook from scratch and make the most of any leftovers. With a bit of dedication and planning it's also possible to grow produce at home in small spaces, including indoors.
Eating a diet of 90% real food and 10% or less processed foods is achievable and may make a significant difference in weight management and overall health. Consider the following guidelines to get you started:
Focus on raw, fresh foods and avoid processed foods. If it comes in a can, bottle or package and has a list of ingredients, it's processed. |
Severely restrict carbohydrates from refined sugars, fructose and processed grains. |
Increase healthy fat consumption. Eating dietary fat isn't what's making you pack on pounds. It's the sugar/fructose and grains that add the padding. |
You may eat an unlimited amount of nonstarchy vegetables; since they are so low in calories, most of the food on your plate should be vegetables. |
Limit protein to less than 0.5 gram per pound of lean body weight. |
Replace sodas and other sweetened beverages with pure, filtered water. |
Shop around the perimeter of the grocery store where most of the whole foods reside, such as meat, fruits, vegetables, eggs and cheese. Not everything around the perimeter is healthy, but you'll avoid many of the ultraprocessed foods this way. |
Vary the whole foods you purchase and the way you eat them. For instance, carrots and peppers are tasty dipped in organic hummus. You get the crunch of the vegetable and smooth texture of the hummus to satisfy your taste, your brain and your physical health. |
Stress creates a physical craving for fats and sugar that may drive your addictive, stress-eating behavior. If you recognize when you're getting stressed and find another means of relieving the emotion, your eating habits will likely improve.
The Emotional Freedom Techniques (EFT) may help reduce your perceived stress, change your eating habits around stress and help you create new, healthier eating habits that support your long-term health. To discover more about EFT, how to do it and how it may help reduce your stress and develop new habits, see my previous article, "EFT Is an Effective Tool for Anxiety." |