Steaks are one of the few indulgences you can still enjoy on a diet, as long as you don't have them with chips.
But your high protein meal may contain more calories than you think - and the number of calories can vary wildly depending on the cut you choose, it's been revealed.
A rib-eye has nearly twice the number of calories of a leaner - and much cheaper - flat iron steak, TV show, Tricks of the Restaurant Trade uncovers.
Nutritionist Amanda Ursell reveals to presenter Sophie Morgan that a rib-eye steak is the most calorific, with 270 calories per 100g.
Amanda says: 'It has the most fat in it. As you can see, it's got the most marbling in it.'
A T-bone steak is the next most calorific, containing 210 calories per 100g. The most expensive cut, a fillet steak, is much leaner, with 155 calories per 100g.
But the leanest of all is a trendy flat iron steak, which has just 140 calories per 100g and only 7g of fat per 100g
Not only are flat iron steaks leaner, but they are cheaper too. Flat iron steaks have become more and more popular in recent years, and were a hit in the US before the UK started to take notice.
A flat iron steak is butchered from the shoulder blade, and is considered a 'secondary cut' of meat, below the likes of fillet and sirloin.
It has a reputation for being tough, but skilled chefs who know how to remove the gristle from the centre of the cut say it's actually one of the most tender - and flavoursome - pieces of meat.