The foods you reach for most, and what research links to body fat.
7 min read
About 40% of cancers diagnosed in the U.S. are in types linked to overweight and obesity.
The CDC identified 13 types of cancer associated with overweight and obesity, and those cancers made up about 40 percent of all cancers diagnosed in the U.S. in 2014. That doesn't mean excess weight caused 40 percent of all cancers: the CDC did not estimate how much of that total is attributable to weight. AICR counts 12 cancer groupings where greater body fatness is a cause. The numbers differ because the agencies group and classify cancers differently.
This lesson isn't about the number on a scale or a goal weight. The research is about patterns across large groups of people, and it tells us where everyday habits matter most.
AICR recommends keeping your weight within a healthy range and avoiding weight gain through adulthood, and limiting fast food and other processed foods high in fat, starches or sugars, which help drive weight gain. The American Cancer Society recommends limiting highly processed foods and refined grain products.
A newer line of research looks at ultra-processed foods themselves. In one study of 197,426 adults in the UK followed for a median of 9.8 years, a higher share of ultra-processed food in the diet was linked to higher rates of some cancers. It's observational and the researchers call the mechanisms 'less understood,' so treat it as a signal, not a conclusion. The evidence linking excess body fat to cancer is considerably stronger than the evidence on ultra-processed foods themselves.
13
cancer types associated with overweight and obesity
CDC, 2017 (IARC list)
about 40%
of U.S. cancers diagnosed in 2014 were in those types
CDC, 2017
12
cancers where AICR says greater body fatness is a cause
AICR
+6% / +16%
relative increase in cancer deaths overall / breast cancer deaths for each 10-point rise in the share of ultra-processed food in the diet (observational)
Imperial College London and IARC, eClinicalMedicine
Researchers commonly use the NOVA system, which sorts foods by how they are processed. Ultra-processed foods are generally industrial formulations made with ingredients and additives not commonly used in home cooking, such as flavorings, colorings, emulsifiers and modified starches. Examples often include packaged cookies and chips, candy, sugary drinks, instant noodles, sweetened breakfast cereals, fast food and many ready-to-eat or ready-to-heat meals. The study above used this category. Not every packaged or frozen food is ultra-processed, and not every processed food has poor nutritional value. The goal isn't to eliminate everything that comes in a package. It's to make minimally processed, nutrient-rich foods the foundation of your everyday eating.
A study of 197,426 UK adults followed for a median of 9.8 years found that for each 10-point increase in the share of the diet that was ultra-processed, overall cancer incidence was about 2% higher and ovarian cancer incidence about 19% higher. Cancer deaths overall were about 6% higher, breast cancer deaths about 16% higher and ovarian cancer deaths about 30% higher. These are relative differences, not increases in anyone's personal risk by that many percentage points.
The researchers adjusted for smoking, physical activity, BMI, alcohol and total energy intake and still saw links. It was still an observational study, so it can't show that ultra-processed food caused the cancers. The researchers also say the reasons behind the links are not yet well understood.
| If you reach for | Try |
|---|---|
| Chips or crackers at 3 p.m. | Popcorn popped at home, or veggies and hummus |
| Cookies or candy | Fruit with nuts, or baked cinnamon apples from the meal plan |
| Fast food at lunch | A prepped salad jar or hummus wrap |
| Frozen dinners | A big pot of soup or stew cooked on Sunday and portioned out |
| Sweetened cereal | Overnight oats with berries and chia, or plain Greek yogurt with berries |
Frozen meals aren't automatically unhealthy. Some are convenient, nutritious options. Compare fiber, sodium, added sugars and protein rather than judging only by the packaging.
Plan the week in Meals
Pick your meals once and shop from the grocery list. Having meals ready makes it easier to choose something nourishing when you're busy.
Prep one thing on Sunday
One pot of soup, one batch of overnight oats, or a few salad jars is enough to change the week.
Make the healthier option easy to reach
Keep fruit and nuts at eye level and the packaged snack out of sight. You don't need to remove every packaged snack.
Myth
This only matters if you're at a high weight.
What research says
AICR's recommendation includes avoiding weight gain through adult life, and the American Cancer Society recommends limiting highly processed foods for everyone.
AICR; American Cancer Society
Myth
Exercise doesn't matter if you don't lose weight.
What research says
In the 1.44-million-person activity analysis, most links between activity and lower cancer risk were similar in people at a normal weight and people who were overweight or obese. Physical activity has health benefits beyond changes on the scale.
NCI, 2016
Myth
Ultra-processed food is proven to cause cancer.
What research says
The research so far is observational. It found links, and the authors say the impact on cancer risk is less understood.
Imperial College London and IARC study
Myth
It's all about willpower.
What research says
AICR says fast food and other processed foods high in fat, starches or sugars can contribute to weight gain. Having a plan, a grocery list and the right foods in your kitchen makes it easier than relying on willpower alone.
AICR on processed foods
Name your top 3
Write down the three packaged snacks or fast-food stops you used most last week.
Swap one this week
Pick one from the table above and put the swap where the old snack lived. Do it five days.
Cook one Sunday batch
Choose one batch recipe from Meals (lentil soup, minestrone or overnight oats) and cook it for the week.
Plan your meals
Pick your dinners in My Menu so the grocery list is ready before the week starts.
- Centers for Disease Control and Prevention: Cancers associated with overweight and obesity make up 40 percent of cancers diagnosed in the United States (press release, Oct 2017)
- American Institute for Cancer Research: Cancer prevention recommendations: weight and processed foods
- American Cancer Society: Guideline for Diet and Physical Activity for Cancer Prevention
- Imperial College London, IARC and others: Ultra-processed food consumption and cancer risk in the UK Biobank (eClinicalMedicine)