Whether loaded with chili and cheese, or served simply with lashings of salt, the humble french fry is undoubtedly America’s favourite deep-fried treat.  But knowing where to order the popular snack can make all the difference to your waistline, as a new book reveals that servings can vary wildly in terms of fat and calorie content. Researchers for Eat This, Not That! 2013: The No-Diet Weight Loss Solution found that one portion can differ by as many as 1,200 calories. McDonald’s french fries were surprisingly among the healthiest on offer at 230 calories and 11g of fat per small serving, however a plate of Chili’s Texas Cheese Fries with Chili and Ranch is a serious diet-buster at 2,150 calories, with a staggering 144g of fat and 6,080mg sodium. Loaded fries aren’t all bad though – if yours aren’t complete without a layer of melted cheese, then head to Steak ‘n’ Shake instead, where a small Bacon Cheese French Fries comes in at a rather less terrifying 360 calories and 20g fat. Thicker-cut steak fries are the safest way to play it on a restaurant menu, the Eat This Not That team reveals, as the higher ratio of potato to oil cuts the fat content down significantly.