 But in the ABCs of the health consequences of obesity, if A is for arthritis, as laid out in my last video, then B is for back pain. Being overweight is not just a risk factor for low back pain, but also sciatica, a radiating nerve pain, and lumbar disc degeneration and disc herniation. Like in the arthritis story, this may similarly be due to a combination of the hefty load, high cholesterol, and inflammation associated with being overweight. Why cholesterol? Autopsy studies and angiography studies show that the lumbar arteries that feed the spine can get clogged off with atherosclerosis and starve the discs in your lower back. B is also for blood pressure. Excess visceral fat. Excess internal abdominal fat can physically compress your kidneys, and the increased pressure can effectively squeeze sodium back into your bloodstream, increasing your blood pressure. Together the combination of obesity and hypertension can have disastrous health implications, but the good news is that even just a few pounds of weight loss can help take the pressure off. Losing weight has been described as a vital strategy for controlling hypertension. Losing around 9 pounds made lower blood pressure about as much as cutting salt intake approximately in half. C is for cancer. As many as three quarters of people surveyed, we're evidently unaware of the link between obesity and cancer, when in fact, based on a comprehensive review of 8,000 studies, excess body fat raises the risk of most cancers, including esophageal cancer, stomach cancer, colorectal cancer, liver cancer, gallbladder cancer, pancreatic cancer, breast cancer, uterine cancer, ovarian cancer, kidney cancer, brain cancer, thyroid cancer, and bone marrow cancer, multiple myeloma. It could be the chronic inflammation of obesity. It could be the high insulin levels due to insulin resistance, besides controlled blood sugars. Insulin is a potent growth factor that can promote tumor growth. In women it could also be the excess estrogen. After the ovaries shut down at menopause, fat takes over as the principal site of estrogen production. That's why obese women have up to nearly twice the estrogen level circulating in their bloodstream, which is associated with increased risk of developing and dying from breast cancer. The data on prostate cancer isn't as strong, though obesity is associated with an increased risk of invasive penis cancer. One of the reasons we're confident the link between obesity and cancer is cause and effect, and not just an indirect consequence of eating poorly, is that when people lose weight, even just through bariatric surgery, their overall risk of cancer goes down. Those experiencing a sustained weight loss, about 40 pounds after surgery, went on to develop around a third fewer cancers over about the subsequent decade than the non-surgical control group of matched individuals that continue to slowly gain weight over time. The exception, though, is colorectal cancer. Colon and rectal cancer appears to be the only malignancy for which the risk goes up after obesity surgery. After bariatric surgery, the rate of rectal cancer death may triple. The rearrangement of anatomy involved in one of the most common surgeries, a ruin-wide gastric bypass, is thought to increase bile acid exposure along the intestinal lining. This causes sustained pro-inflammatory changes even years after the procedure, which is thought responsible for the increased cancer risk. In contrast, losing weight by dietary means has the potential to decrease obesity-related cancer risk across the board. That's what my book, How Not to Diet, is all about. D is for diabetes. As laid out in a consensus statement from the International Diabetes Federation, obesity is considered the single most important risk factor for the development of type 2 diabetes, the leading cause of kidney failure, the leading cause of lower limb amputations, and the leading cause of adult onset malignness. Ironically, many of the leading drugs used to treat diabetes, including insulin itself, actually cause further weight gain, creating a vicious cycle. So again, using lifestyle medicine to instead treat the underlying cause is not only safer, simpler, and cheaper, but also can be most effective.