A new study has identified obesity and extra weight as the biggest cause of cancer. Bryan Hubbard reports
Obesity has just been recognized as the main cause of cancer, responsible for nearly half of all cases. It has overtaken smoking as the primary culprit and is being linked to up to 32 types of the disease, a major study has discovered.
It accounts for 40 percent of all cancer cases, which suggests it could be responsible for 760,000 new cases in the US and 150,000 in the UK every year. An obese person is twice as likely as a smoker to develop cancer—smoking accounts for 20 percent of all cancers and about 80 percent of lung cancers.
According to Cancer Research UK, excess body fat can raise levels of growth hormones, which instruct cells to divide more often. Excess fat also starts an inflammatory cycle, which causes cells to divide quickly. Both of these processes are precursors of cancer.
Although obesity has always been recognized as a major cause of cancer, experts had linked it to just 13 types, including breast, bowel, uterine and kidney cancers. They estimated it was responsible for one in 20 (5 percent) of all new cases.
But researchers from Lund University in Sweden have discovered it’s responsible for 32 different cancers and around 90 subtypes, including malignant melanoma and cancers of the stomach, small intestine, pituitary glands, head and neck, vulva and penis.1
Lead researcher Ming Sun said, “Our findings suggest that the impact of obesity on cancer might be greater than previously known, in that it is a risk factor for more cancers, especially of rarer kind.”
The researchers tracked the weight, health and lifestyle of 4.1 million people for around 40 years, during which time 332,500 developed cancer. In 40 percent of cases, the person was overweight or obese, and the researchers estimate that every five-point increase in the BMI (body-mass index) score raises the risk of cancer by 24 percent in men and 12 percent in women (see below).
Obesity has become an international health crisis, with cases doubling since the 1990s. Around 74 percent of Americans and 64 percent of Britons are obese or overweight. Health guardians are promoting the wider use of weight-loss drug semaglutide to counter the epidemic. It’s marketed as Wegovy, Ozempic or Rybelsus and manufactured by Danish drug giant Novo Nordisk.
Although sales of semaglutide have doubled in the last year, the drug has only a modest effect on weight loss. One study, involving 1,961 people with a 30-plus BMI score, concluded that it helped reduce weight by less than 15 percent after 68 weeks (one year, four months) of treatment. The group not taking the drug lost 2.4 percent of their weight.2
Semaglutide, which is administered as a weekly jab, works on areas of the brain that regulate appetite by increasing feelings of fullness. It also slows movement of food through the digestive tract, promotes the use of fat for energy and reduces blood sugar (glucose) levels by releasing insulin to break it down.
But it’s a dangerous drug. Semaglutide carries a “black box” warning—the highest alert possible by America’s drug regulator, the FDA (Food and Drug Administration), before a drug is pulled from the market—because it raises the risk of thyroid tumors or cancers and ileus, or intestinal blockage. Novo Nordisk has also warned that semaglutide can cause pancreatitis (inflammation of the pancreas), hypoglycemia (low blood sugar), digestive problems, serious allergic reactions and gallstones.
The UK’s drug watchdog, the MHRA (Medicines and Healthcare products Regulatory Agency), has received 7,254 reports of adverse reactions to Wegovy, Ozempic and Rybelsus since 2019. They included 20 deaths, 3,819 gastrointestinal disorder cases and 700 nervous system disorder cases.
A safer and more effective way to lose weight is to eat a healthy diet and avoid processed food and sugary drinks. Around 64 percent of the calories in the typical Western diet are made up of ultra-processed and processed food. For every 10 percent increase in the amount of processed food consumed, there’s an 18 percent rise in obesity in men and 17 percent in women, estimate researchers from São Paulo University in Brazil.3
Other researchers also see a direct link between processed foods and obesity. People need to eat a certain amount of protein, but processed food is mainly carbohydrates and fat, and so the body drives them to eat more of it to meet their protein needs, say researchers from the University of Sydney.4
If the association is clear, why isn’t the message hitting home? Cardiologist Dr Aseem Malhotra says the food industry has deflected blame by getting celebrities to endorse their processed food and drinks and pointing to inactivity as the culprit.
“It is time to wind back the harms caused by the junk food industry’s public relations machinery,” he and his colleagues wrote in an editorial. “Let us bust the myth of physical inactivity and obesity. You cannot outrun a bad diet.”5
Although obesity—and, from that, cancer—are the result of the modern processed diet, our hormones could also be contributing to the problem. In the 1990s, biologists discovered that our appetite and fat levels are controlled by two hormones, leptin and ghrelin.
Leptin is a protein hormone made in our fat stores that tells the brain when we have eaten enough but also lets it know when we’re hungry and need to eat. It explains yo-yo dieting, when people lose weight and then put it back on repeatedly, because losing fat also means we lose leptin and its ability to tell the brain we’re full.
Ghrelin, the “hunger hormone,” is a gastric amino acid peptide that stimulates the secretion of growth hormones and increases levels of fat in the body. Corresponding to leptin, it’s the other side of the hormonal coin, and its levels rise before we eat and decrease afterward. Essentially, it’s the key regulator of energy in the body, and the higher ghrelin levels are, the hungrier we feel.
Researchers have noted that obese people suffer from “leptin resistance,” in which the brain doesn’t recognize the hormone’s messages. The brain assumes leptin levels are low and stimulates hunger pangs.
Obese people also have abnormal levels of ghrelin, either low or downregulated. Levels are often affected by higher amounts of leptin and insulin, which breaks down sugars from carbohydrates and causes excess amounts to be stored as fat.
Even more than insulin resistance, which leads to type 2 diabetes, leptin resistance could be the key to understanding obesity. A calorie-controlled diet seems to contribute to the leptin-ghrelin imbalance, as do poor sleeping patterns, but it’s also the result of seeing food purely in terms of calories and not quality.
Processed foods in all forms—including ready-meals, white bread, pastries, white rice, pastries, cakes and anything else that has a high GI (glycemic index) score—are at the heart of the obesity epidemic and, by default, of cancer.
1. Eat a highly varied, fresh, organic diet composed mostly of highly nutritious, colorful fruits, vegetables and herbs. Strive to eat nine or 10 fruits and vegetables every day.
2. Eat vegetables that help fat regulators such as cruciferous vegetables like broccoli and cabbage, carrots, leeks, onions, spring onions, garlic, asparagus, bell peppers, arugula/ rocket, romaine lettuce, spinach and tomatoes.
3. Eat fruits that stoke fat-burning hormones such as bananas, apples, blueberries, cherries, oranges, grapefruit and pomegranates.
4. Add herbs that aid fat-burning such as ginger, ginseng, cinnamon, bilberry, chamomile, chasteberry, green tea, peppermint oil, turmeric, dandelion, aloe vera and echinacea.
5. Use spices liberally in your food.
6. Eat fresh, uncooked and unsalted nuts such as walnuts, flaxseeds, sesame seeds and almonds.
7. Ensure an adequate intake of omega-3 fats from high-quality animal sources such as cold-water fatty fish like salmon and tuna. Good plant sources are walnuts, flaxseed and pulses (such as soy, kidney and navy beans).
8. Don’t eat late at night.
9. Include protein in your breakfast.
10. Get seven to eight hours of sleep a night—no more, no less.
11. Cut out or cut down on refined sugar in all its forms. That means no processed foods and drinks.
12. Engage in regular sweat-producing exercise to increase leptin production, although following the right diet will cause leptin levels to regularize naturally.
13. Look to grains with a lower GI score, such as pasta, brown rice, quinoa, millet, oats and barley.
14. Watch your carbohydrate intake and stay off the white stuff: avoid white bread, potatoes, white rice, pastries, cakes and high-GI-score drinks, such as beer and sodas.
15. Take high-quality supplements that are rich in B vitamins, particularly B12, plus omega-3 fatty acids, magnesium, zinc and coenzyme Q10, which helps to counteract inflammation.
16. Avoid fake low-calorie foods and particularly artificial sweeteners and diet soft drinks.
17. Eat three good meals a day and don’t snack with at least 12 hours between your last meal and breakfast (including the time you’re sleeping).
18. Drink plenty of water as well as green and black teas and orange, blueberry, cherry, pomegranate and vegetable juices.
Your BMI (body mass index) score is one measure of obesity—and its critics say it’s a pretty unreliable one. It can’t tell the difference between fat and muscle, which is heavier. As a result, for instance, an athlete could be classified as obese despite having low body fat.
To calculate your BMI, square your height in meters and then divide your weight in kilograms by that number. Here’s how that calculation would go if you are 1.73 m (around 5 ft, 8 in.) tall and weigh 70 kg (around 11 stone or 155 lb).
1.73 × 1.73 = 2.99
70 / 2.99 = 23.4
If math isn’t your strong suit, many online calculators are available, and you can just plug your numbers in. Your score will fall into one of the following categories.
Underweight: less than 18.5
Normal: 18.5–24.9
Overweight: 25–29.9
Obese: 30–34.9
Morbidly obese: 35 and up
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