Cancer may not be one of the first things you think about when it comes to the health risks of being overweight or obese, but it probably should be. As many as twelve different cancers have been linked to weight, including cancers of the colon, endometrium, kidney, esophagus and breast.
With such a broad impact, it’s been estimated that about 120,000 deaths from cancer could be avoided each year in the United States if everyone stayed at a healthy weight throughout life. Tack on lower rates of heart disease, diabetes and blood pressure and it’s hard to ignore the importance of keeping weight in check.
So what exactly is a healthy weight? Enter the strange sounding “body mass index” – or BMI. BMI uses a special calculation of weight and height to get an idea of how much extra fat someone may be carrying.
For adults, a BMI of 18.5-24.9 is considered a healthy weight; a BMI of 25-29.9 is overweight, and anything 30 and over is obese. While BMI is not a perfect measure, for most people it does a good job estimating excess weight. To see where you fall on the scale, visit our BMI calculator.
Of course, the health risks from overweight aren’t constant throughout one category and then immediately jump up when you cross into another. It’s much more a steady increase. As BMI goes up, the size and number of health risks start to go up. Even within the upper end of the healthy range, the risk of diabetes, high blood pressure, heart disease and some cancers starts to rise as BMI creeps higher.
Below are some key cancers that have been linked to weight:
Obesity has been shown in many studies to raise the risk of both colon cancer and adenomatous polyps, which are precancerous growths that can turn into cancer. It’s not exactly clear how weight increases risk. One possibility is that extra weight increase insulin levels in the blood, which may then stimulate abnormal cell growth in the colon.
For the past four decades, study after study has shown that the more a woman weighs, the greater her risk of endometrial cancer. One possible reason is that overweight women tend to have higher levels of estrogen and lower levels of progesterone than lean women do. The combination of high estrogen and low progesterone has been linked to endometrial cancer.
There is very strong evidence that overweight and obesity increase the risk of kidney cancer. Exactly how weight increases risk, though, is less well known. It could relate to inflammation, increased insulin levels, and higher blood pressure, each of which can be the result of being overweight and each of which has also been linked to kidney cancer.
The esophagus is the tube that carries food down the throat and into the stomach, and there is a great deal of evidence that obesity raises the risk a specific type of esophageal cancer called adenocarcinoma of the esophagus. It’s not exactly clear why, but there’s a chance it’s related to gastric reflux, where stomach acids leak up and irritate the esophagus. Gastric reflux is an established risk factor for adenocarcinoma, and it can be more common in obese adults.
It’s well established that weight gain increases the risk of breast cancer in postmenopausal women. The evidence is less clear for breast cancer in premenopausal women. Some studies show that being overweight can actually lower the risk of breast cancer before menopause, while other findings suggest that even short-term weight gain before menopause can increase risk. Wherever the findings ultimately fall, it’s important for women to try to maintain a healthy weight throughout life. Most breast cancers develop after menopause. And, for most women, the weight they put on before menopause will likely stay with them after menopause as well.
Weight gain likely increases breast cancer risk by raising levels of the hormone estrogen, which can promote cancer growth. After menopause when a woman’s ovaries stop producing as much estrogen, fat tissue becomes a major source of the hormone. The more weight a woman’s gained, the greater the source of estrogen after menopause.
Prostate cancer is the most common cancer in men, but unfortunately, there are only a handful of lifestyle factors that can help prevent the disease. There is very good evidence that being overweight increases the risk of the most serious type of prostate cancer. Exactly why this is isn’t clear, but it may be related to increased inflammation and altered hormone levels linked to being overweight.
In addition to the cancers above, there’s also good evidence that weight gain and obesity increase the risk of pancreatic cancer, gallbladder cancer, liver cancer, ovarian cancer as well as leukemia, lymphoma, and multiple myeloma.
Although keeping weight in check can be a tall order in this day of dollar menus and smartphones, it’s well worth the effort. The cancer benefits alone are huge. When the impact on heart disease, diabetes, blood pressure, and good old-fashioned quality of life are added, the benefits become enormous. Try these simple steps:
- Exercise, exercise, exercise. Being active is one of the best ways of controlling weight.
- Watch the calories. It sounds simple, but it’s worth saying: calories matter when in comes to weight gain and weight loss. When you sit down for a snack or meal, take some time to think about how much you’re eating and when you’ve had enough.
- Weigh yourself – every day. Weighing yourself regularly can help you keep on track with your weight goals.
- Go Mediterranean. A diet rich in fruits, vegetables, whole grains, and healthy oils (like olive oil) can make you feel full, help regulate your appetite, and actually taste really good.
- Choose smaller portions and eat more slowly. Slow down and give your body a chance to feel full before you move on to seconds.
- Be a mindful eater. Food is big business, its main goal is to get you to eat. Try to listen to what your body is telling you, not what the food business wants you to hear.