Hi! I'm Stelios Pantazis. I'm a doctor and I specialize in medical nutrition and metabolic disorders. Today, I'd like to talk about an impressive study that was published a few years ago and links weight with cancer. This was a very significant study, because it showed without doubt that many types of cancer are linked with increased weight, hoping to give one more motive to overweight people to do something to deal with this problem. Before talking about the study, I'd like you to calculate your Body Mass Index, which shows if your weight is healthy for your height. To calculate this index, divide your weight in kg by your height in metres. I want you to find your weight, but not your ideal weight, not the weight you'd like to have, not the best weight of the last five years, but your real, current weight. And then, your height. Again, not the height your mother told you, but your real height. Because many people come to my office and tell me their height that's different from what we measure. Therefore, be fair and honest to yourself, so that you know the real risk. To spare you the trouble of doing the math on your own, I'm giving you a table that links the height, on the vertical line, with weight, on the horizontal line. You just have to find your weight on the horizontal line, approximately, because it shows the weight per five kg, you can find the middle; if you're not exactly 91 or 95, 93 is somewhere in the middle. Go down, find your height and see where you're at. 29, 30, 35, the index is a number. Devote some time to do this now with me. Great. It's not difficult. Let's see if your weight affects the risk of cancer. First of all, let's see the study, which is this, for anyone who's brave enough to try to find it. It's a very famous study that was published in The Lancet, one of the most famous medical journals in the world. It's been published since the 1800's in the United Kingdom. This study examined 22 types of cancer, it obviously did not examine every type, but the 22 most frequent ones, in 5.24 million adults, therefore a very representative sample. The study pertains to the United Kingdom, of course. These 22 types of cancer are 90% of the cases in the United Kingdom. We'll see the results of non-smokers, because the results of smokers are a little confusing, because they pose problems concerning lung cancer etc., therefore we prefer a clear picture. Let's see the results. To help you understand these lines, this is what happens: You can see a vertical line, an X and a horizontal line going through the X. The vertical line defines if the cancer correlates with weight or not. When the X is on the right side of the line, this means yes, this type of cancer correlates with weight. Be careful. The small lines on the side are our degree of certainty that this answer is yes. Therefore, in the first example, oral cavity cancer has an X on the right side of the line. This means it correlates with increased weight. But because the horizontal line crosses the vertical line, this means that we're not certain, therefore no. If we had a much bigger sample, it could finally be yes. We'll see this in future studies. For the time being, it seems that the answer is probably no. This is why I wrote NO in green. This type of cancer does not probably correlate with increased weight. Next, we see oesophageal cancer. Because the horizontal line ends on the right of the vertical line, we're certain that oesophageal cancer correlates with increased weight. Stomach cancer, marginally, for the time being, no, this dataset can't confirm this. Colon cancer, yes. In fact, the shorter the uncertainty horizontal line, the more certain we're for the result. The longer it is, the higher the uncertainty. Of course, the uncertainty is attributed to the small number of cases. In general, frequent types of cancer have a short horizontal line and the most uncommon ones have a longer line. So, colon cancer, yes, and this is a significant yes. Rectum cancer, no, as it seems. This is marginal too. Liver cancer, certainly yes, unfortunately. Gallbladder cancer, yes. Although the horizontal line is very long, it doesn't cross the vertical line. Certainly yes, therefore. Pancreas cancer also correlates with increased weight. Lung cancer, of course not. It mainly correlates with smoking. Next, we can see some types of cancer that don't correlate with weight either. Melanoma, breast cancer in women before menopause. This is very interesting. Breast cancer in women before menopause does not correlate with weight, but, after menopause, it correlates with weight. In breast cancer before and after menopause, the horizontal lines are short, which means that we're quite certain for the results. And this is an impressive and unexpected difference. You can see that weight affects a type of cancer differently before and after menopause. Cervix cancer also seems to correlate with increased weight. Uterus cancer, also yes. Ovaries cancer, yes. Therefore, gynaecological types of cancer, except for breast cancer before menopause, correlate with increased weight. Prostate cancer in men, no. Diet plays a role here, but increased weight doesn't. Don't forget, we're examining increased weight here, not diet. Because diet plays a role in this cancer, but weight doesn't. Kidney cancer, yes, it correlates with weight. On the contrary, bladder, brain and CNS, and thyroid cancer don't seem to correlate with increased weight, although in thyroid cancer, no is marginal. And finally, lymphoma and myeloma, no, while leukaemia, yes. That's impressive. I'd like to spend a few seconds on some other graphs, because the study goes further and says how much weight affects cancer. You can see these two graphs here about gallbladder and leukemia. Both types of cancer correlate with increased weight, namely increased weight increases the chance of one of these two types. But there's a big difference here. In gallbladder, as weight increases, the cancer risk increases steeply. People with a BMI of 30 have 60-70% more chances than people with a BMI of 22. But people with a BMI of 40 have 2.5-3 times more chances of developing gallbladder cancer. Although leukemia correlates with increased weight, as the weight increases, the line stays low, namely they do correlate, but not that much. If you have a BMI of 30 instead of 40, the difference is not that big. It correlates with weight, but not that linearly. Here are two more types that are known to correlate with weight. Liver and uterus cancer. In uterus cancer, the line spirals and increased weight increases the chances of this cancer by many times. Therefore, you need to be careful. You've heard a few things about how weight increases the chance of some types of cancer. You should bear these in mind. If you know someone that has a weight problem, you should motivate and help them deal with it. If you thought this was interesting, please give us a thumbs up. Share it with people who you think might find it interesting and suggest subjects in the comment section. Thank you very much!

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