 SWAN, which stands for Study of Women's Health Across the Nation, is by far the largest evaluation of menopausal symptoms in history, studying 16,000 American women between the ages of 40 and 55. They found that women over a body mass index of 27 or higher were significantly more likely to suffer from hot flashes or night sweats, stiffness or soreness, and urinary leakage. A BMI over 25 is considered overweight 30 obese and the average US BMI, 29.8. Since fatty tissue is a source for estrogen, one might expect the reverse, but the link between excess body fat and worse menopausal symptoms indeed seems causal, since women randomized to a weight loss intervention experience significant improvement in hot flashes in effect that may extend to bariatric surgery. In the SWAN study, smoking and inactivity were also associated with more frequent symptoms. It's always a good idea to quit smoking and exercise, but there are no interventional trials on smoking cessation and menopausal symptoms to prove cause and effect, and randomized controlled trials of exercise failed to show any symptom relief. Of course, you could just take hormone therapy, but at the cost of significantly higher risk of suffering on a heart attack, stroke, blood clot, breast cancer, or gallbladder disease. What can we do naturally to avoid the extra clots in cancer? Hot flashes, also referred to as hot flushes, are the most common menopausal symptoms for which women seek treatment. They afflict up to 80 to 85% of European and American women lasting, along with night sweats, for an average of more than seven years. But these symptoms are not universal, though in North America they may be considered inevitable. If you noticed, in Japan, for example, only 15% may be affected. In fact, there isn't even a term for hot flash in the Japanese language. The absence of even a word for it in Japan is often more remarkable, because Japanese is said to be infinitely more sensitive than English in describing bodily states, with all sorts of extremely subtle distinctions for somatic sensations. For example, there's all sorts of specific terms describing different sensations. Like in Japanese, there are 20 or more words just to describe the state of one's stomach and intestines alone. But hot flashes appeared to be so unusual there, researchers had to come up with ways to describe it in Japanese surveys. Investigators suspected it might be the soy. Dietary surveys have estimated that soy isoflavone intake, the phytoestrogens in soy, is at least 10 times higher than in Europe or North America, and one comparison of urine metabolites revealed Japanese women have a hundred times more phytoestrogens flowing through their body at any one time. To see if this might be playing a role, researchers followed 1,000 Japanese women over time, starting before they reached menopause to see if soy consumption was linked to whether or not they developed hot flashes. Women eating around 4 ounces of tofu a day only had half the risk compared to women only eating an ounce or two a day. The researchers concluded our findings suggest that consumption of soy products is a practical strategy for preventing hot flashes, but only if interventional trials prove they actually work, which I'll cover next.