There tends to be a lot of confusion about fat (what are the good fats? What are the bad fats? Should I avoid fat?). To make things simple, it’s important to know that fat is a vital nutrient that we need...we just don’t need too much. Fat is a necessity for our bodies - an important part of inflammation control, brain development, cognition,and blood clotting. It helps keep us warm, keeps our skin and nails healthy,and provides an extra stash of energy when needed. It also affects cancer prevention, treatment and survivorship as it can have an effect on our body weight and overall health.

Cancer Prevention

One might consider the following: the more cells you have, the more chance there is that something can go wrong. It’s a thought-provoking consideration, as obesity has been clearly linked to colorectal and other cancers (in addition to a variety of other health issues like high blood pressure, heart disease and diabetes). What research suggests time and time again is that people with a higher body mass index (BMI) have a heightened risk of developing colorectal cancer. BMI is calculated by dividing weight in kilograms by height in meters squared. For most, a BMI of 30 and over is considered obese, though it is important to talk to your doctor as this isn’t always the case (for example, people who weigh more due to muscle mass). In addition, newer studies show that carrying fat around the midline is also a good indicator of cancer risk.
Jessica Ianotta, registered dietitian and specialist in oncology nutrition (CSO) at Savor Health states, “since excess fat mass is linked to certain types of cancer, it is important to stay at a healthy weight. The best way to lose fat mass is to exercise regularly and eat a calorie controlled diet. Eating a diet rich in fruits, vegetables, lean protein and whole grains can provide the fuel your body needs without the excess calories. Also, it is important to eat often throughout the day to keep up your metabolism. Skipping meals, if a daily practice, can result in a slower metabolism and may make it more difficult to achieve a healthy weight.”
The main takeaway: maintaining a healthy weight, and watching your waistline is a good way to reduce colorectal cancer risk.

Cancer Treatment

For cancer patients and survivors, being obese leads to poorer outcomes. Being overweight is a risk factor for recurrence and new research suggests it could reduce the effectiveness of chemotherapy. According to the study, fat cells absorbed a chemotherapy drug, rendering it less effective in treating the actual cancer. While this was the first study of its kind, with a focus on daunorubicin (a chemotherapy agent used to treat leukemia), the concept is worth considering as researchers try to understand the poorer outcomes associated with obese cancer patients.
According to Dr. Harvey Murff from Vanderbilt University, “obesity very clearly increases the rates of surgical complications in patients undergoing surgery for colorectal cancer.”
In fact, a study from early 2017 indicates that one month of “prehabilitation” (exercise, nutritional supplementation and relaxation practices) can improve post-surgical outcomes. The main takeaway: obesity could affect cancer treatment and practicing a healthy lifestyle before treatment can be beneficial.

Cancer Survivorship

Maintaining a healthy BMI and weight is very important for cancer survivors. Not only could it increase quality of life, it also reduces the risk of comorbidities (like diabetes and high blood pressure), risk of cancer recurrence and could lengthen the number of years lived.
According to Dr. Murff “To date, although not entirely consistent, being obese is associated with a decrease in survival in colorectal cancer and possibly an increase risk of recurrence. With respect to chemotherapy, a few studies have found that bevacizumab may be less effective in obese patients with colorectal cancer.”
Per gram, fat has around nine calories. This is nearly double the amount of calories other vital nutrients such as carbohydrates and protein contain. Any calorie that is not used up by the body is stored as fat. When considering weight loss, it’s important to know that the best way to lose weight is to burn more calories than you consume--that means either working out more, or eating fewer calories. It’s important to distinguish between losing weight on purpose, and losing weight due to the negative effects of cancer treatment.
Dr. Murff adds, “It is always important to maintain a healthy weight, however, it is harder to determine the impact of weight changes after CRC treatment and their effects on survivorship. This is because losing weight after treatment often might be related to a greater burden of disease or other factors and not necessarily mean the same thing that deliberate weight loss in someone who is overweight.”
For example, for some, eating is a challenge that’s hard to face. Mouth sores, constipation, nausea, vomiting and other side effects can really reduce a person’s drive to eat. Make sure to talk to your doctor or nutritionist about foods that are easy to eat while in treatment and eat what you can.
According to Jessica Ionnotta, “even if a cancer patient is losing weight from cancer treatment, it is important to eat a healthy and balanced diet, while limiting the intake of unhealthy fats. Healthy fat sources, such as avocado, olives and olive oil, and nuts and nut butters are great options to add extra calories to promote weight gain. With that being said, sometimes patients can only tolerate or “stomach” certain foods while they are undergoing treatment and some of these healthy fats can be less appealing to them. When experiencing weight loss, calories are most critical and it is better to eat what you can tolerate best.”
Main takeaway: Maintaining a healthy, balanced diet is key--and eating fewer calories does not necessarily mean eating less food, but rather, eating foods that are nutrient dense, such as fruits and vegetables.