Starting in your 40s, it's easier than ever for the kilos to creep on - and tougher to take them off. Thanks to a slowing metabolism you could be burning 1,250 fewer kilojoules (300cal) per day than you did in your early 20s. What's more, falling oestrogen levels during perimenopause and menopause (which begin in your early 40s) can cause insulin sensitivity, which makes it harder for your body to control the amount of sugar in your blood, says bariatric surgeon Dr Caroline Cederquist. This can make your blood sugar levels more prone to spiking and crashing, which can increase your urge to snack - especially on high-carb, sugary junk, Cederquist says.

Put it together, and it's no wonder so many women over 40 end up hitting a weight loss wall. But it doesn't have to be that way. With a few smart moves, you can outsmart your slowing metabolism and get lean - for good.