Processed Foods and Weight

Here’s the impact of choosing apple pie over apples too often

We all know the difference between apples and apple pie. Apples can often be eaten off the tree with just a quick rinse, whereas apple pie involves peeling, chopping, adding a bunch of ingredients (including sugar), and then putting all of that applesauce-like filling into a pie crust before baking.

The more steps and ingredients that are involved in making any food—like the pie—the more “processed” it is and the farther away it is from its natural, unprocessed state.

Eating a lot of “ultra-processed” foods has well-established links to weight gain and related conditions such as high blood pressure, heart disease, type 2 diabetes, metabolic syndrome, some cancers, and all-cause mortality.

What is an “ultra-processed” food?

Foods can go through many levels of processing, often by adding many ingredients to it, and the end product may not resemble the original food at all. Think of the difference between an apple, applesauce, and an apple pie. These show you the changes made to a food as it goes through more and more processing.

According to the NOVA classification, there are four groups of food processing:

  1. Unprocessed or minimally processed – Fresh, dry, or frozen foods where inedible parts are removed and nothing is added, e.g. whole or sliced apple.
  2. Processed culinary ingredients – These are oils, fats, sugars, and salts that are derived from nature, but are processed, e.g., olive oil, butter, maple syrup, etc.
  3. Processed foods – Foods that are canned, pickled, smoked, cured, or fermented—often with the addition of oils, sugars, or salts, e.g., sauerkraut, cheese, wine, beer, etc.
  4. Ultra-processed foods – Foods that undergo many processes and modifications, e.g., packaged snacks, frozen meals, sugar-sweetened beverages, etc.

Many processed foods, especially ultra-processed foods, tend to be higher in saturated fat, sugar, salt, and calories, while being lower in healthful fibre. Ultra-processed foods are often designed to be very profitable, convenient, highly palatable, shelf-stable, and affordable. These foods also tend to be very well marketed and advertised. This is why these foods have become very popular in the “west” and are associated with the “western” or “Standard American” diets.

Ultra-processed foods and obesity

Obesity is linked with several health and lifestyle factors, one of which is the consumption of ultra-processed foods.

When it comes to biomarkers of disease, several studies show that consumption of ultra-processed foods increases the rates of:

  • weight gain/overweight (27-36% higher)
  • waist circumference (33-39%)
  • abdominal obesity (30-49% higher)
  • obesity (51-79% higher)
  • metabolic syndrome (79-81% higher)
  • death by any cause (49% higher). 

This means that people who consume more ultra-processed foods have higher risks for all of these conditions than people who eat less of it. While this doesn’t mean that obesity and disease rates are caused solely by intake of ultra-processed foods, diet is one factor that seems to matter quite a bit when it comes to health.

How ultra-processed foods can affect weight and disease risk

Ultra-processed foods have several short-term effects on the body that, when consumed frequently, may lead to longer-term health effects. These short term effects include the fact that they:

  • Tend to not be too filling (“low satiety”) because they are low in fibre, have softer textures, and impact hunger-related hormones—all of which can lead to eating more than necessary in order to feel full.
  • Are “hyperpalatable” because they’re higher in sugar, salt, and fat, and this can result in a preference for ultra-processed foods over less-processed foods that tend to be more filling and nutritious, but not as delicious.
  • Increase blood sugar levels (“highly glycemic”) because of their higher levels of sugar and lower levels of fibre.
  • Contribute to a gut microbiota that tends to be inflammatory (because ultra-processed foods tend to have less fibre and more fat) and this inflammation can increase the risk for heart disease and other conditions.
  • May contain endocrine-disrupting compounds in their packaging that promote inflammation, oxidation, insulin resistance, and increased weight, all of which can increase risk for heart disease, diabetes, and high blood pressure.
  • Contain different levels of nutrients than minimally-processed foods (often lower levels of essential nutrients and higher calories), so this can contribute to weight gain and chronic diseases like heart disease and diabetes.

How to reduce your intake of ultra-processed foods

As you can see, it’s best to minimize your intake of ultra-processed foods and maximize the amount of unprocessed or minimally-processed foods you consume. There are lots of things you can do to reduce your intake of ultra-processed foods. You can try:

  • Reducing the amount of sugar in your beverages by diluting them with plain water or replacing them with water or herbal tea.
  • Swapping some ultra-processed foods for more nutritious options, e.g., a baked potato instead of fries, whole grain pasta or bread instead of white, or a sliced avocado instead of pre-packaged guacamole.
  • Enjoying some less-processed snacks when you’re hungry, e.g., fruit, vegetables, nuts, seeds, or boiled eggs.
  • Planning out your meals and shopping lists in advance so you’re not left hungry and ready to grab just anything because it’s quick and easy.
  • Choosing to purchase and keep less ultra-processed food at home so you have fewer to choose from when you’re hungry.
  • When considering pre-packaged foods, try checking the Nutrition Facts labels and opt for those that are lower in salt, sugar, and saturated fat, and are higher in fibre.


Crimarco, A., Landry, M. J., & Gardner, C. D. (2021). Ultra-processed Foods, Weight Gain, and Co-morbidity Risk. Current obesity reports, 1–13. Advance online publication.

Backgrounder articles:

About the study:

  • The purpose of this study was to review studies published between 2016-2021 that looked at the links between ultra-processed food consumption and weight gain and/or risks of other diseases. The researchers included several studies published around the world, as you can see in the tables linked below: 
  • “It is worth noting that obesity is a multifactorial disease with many related lifestyle contributors. Given the majority of research on UPFs is observational in nature, residual confounding is possible.” This means that there is a link between the intake of ultra-processed foods and obesity, but the way the studies were done (i.e., they’re observational), they can’t definitively prove that the consumption of ultra-processed foods *caused* excess weight and/or diseases. Plus, we know that obesity is a complex disease that involves many factors, one of which is the consumption of ultra-processed foods (i.e., can also include factors such as genetics, levels of physical activity, other diseases/mobility issues, medications, mental health, socio-economic status, difficulty accessing fresh foods, etc.)
  • When I mention the “increased rates” in percentages, this means that people who eat more ultra-processed foods have a higher risk of getting that condition. For example, “overweight (27-36% higher)” means that for every 100 people with overweight who do not eat a lot of ultra-processed foods, you will have 127-136 people with overweight who do eat a lot of ultra-processed foods. So the risk increases by 27-36%. 
  • Conclusion: “While awaiting further research, recommendations to limit or restrict UPF [ultra-processed food] consumption would likely lead to more benefit than harm.”
  • Note that all studies have limitations. This study is a review of many studies published in the past 5 years on the topic of ultra-processed foods and weight and/or disease risk. This makes it a strong study. However, as noted above, most of the research it includes is “observational” not “experimental” for the simple fact that experimental nutrition studies are very difficult and expensive to conduct. Plus, nutrition studies are difficult—but not impossible—to “blind” (e.g., people know whether they’re eating broccoli or fries, but they may not know if they’re eating a high- or low-sodium diet). This means that this review of several studies is another pretty strong piece in the puzzle linking ultra-processed foods to excess weight and chronic diseases, but does *not* confirm that one “causes” the other (and as mentioned above, we *know* that there are other factors involved, like genes).
  • Therefore, we can’t say that eating more ultra-processed foods *causes* weight gain or chronic diseases, we can say that it increases risk/chances or it’s associated with an increased risk/chance (correlation does not equal causation). Here’s a blog post I wrote on this concept:
  • Study strength is rated a 7/7 according to this chart (review of several studies, but note that many of the studies included are rated at a 4/7 or 5/7):