When you turn 30, upsetting things happen. Apparently. You start to slow down, you ache more, and you probably don't even own a house yet.

Yes. Your big birthday party has finished and a deep, harrowing feeling of despair has set in. You might also look forward to putting on weight and getting grey pubic hair. We can't fight it. The human body, as we know, is ever-changing. Things happen – things that scientists say come into effect, or start to, when we hit the big three 0.

Weight

It's harder to shift when you're out of your 20s. It's because your metabolism begins to slow. For women, pregnancy might play a part too. Stress can also cause weight gain, as a reactionary release of hormones can encourage fat storage increases, nutritionist Jane Michell said.

The National Health and Nutrition Examination Survey found that the average person typically puts on one to two pounds per year from their youth up until their mid-30s, according to the Washington Post .

Sex drive Goodbye, sex? Actually, researchers say that women aged between 27-45 are hornier. They fantasise more, it seems, and have more sex in general than in their early 20s right up until menopause.

But while a higher sex drive might be a good thing, the reason is due to declining fertility, a study by Personality and Individual Differences suggests. For men, testosterone levels decrease after 30, which can mean a fall in libido. It happens at a rate of about one per cent a year. By 70, the decrease can approach 50 per cent, according to Livestrong . 

Hormones Hormone changes in our body, heightened with age, can also have an impact on body fat, hair loss, mood swings, and erectile dysfunction. So that's great.

OK