I'm not a fan of following guides and tables when it comes to working out ideal weights. You generally know by looking at someone if they're a healthy weight or not. But for those who can't tell or who maybe need a number to jolt them into action the BMI is a useful guide.
It can be wildly inaccurate so should be used with care - I once had a boyfriend who was very into weight training and had an impressively low amount of body fat but was told by the GP practice nurse that he was obese and should lose weight, obviously too busy looking at his chart to notice this was clearly not the case!
Your body fat percentage is the most truthful measure, if you can get an accurate reading, but save the money on the scales and buy a tape measure! I think periodically measuring yourself with a tape measure is one of the best ways to keep tabs on whether you're inshape or not and can pick up other issues such as waist to hip ratio which tells you your insulin profile and risk of diabetes amongst other conditions, and if you're losing or gaining in particular areas.
Trying on a pair of skinny jeans is another super easy way to keep tabs on your weight - if you can get into the same clothes you wore five years ago you're doing well!
Still when the bbc published this article on obesity I couldn't resist their cute little BMI world comparison tool.
It turns out that if everyone had the same bmi as me (21) then it would remove 35,192,090 tonnes of total weight from the world population! Put in your weight and height and it will also tell you where you are relative to your country (i'm in the bottom 10%) and which country average you match (Bangladesh).
So if you need a bit of motivation to lose some weight, click on the articlee below and scroll down to calculate your bmi