A regulation size 3 Musketeers Bar weighs 60.4g and has 260 calories.

One gram of sugar has four calories.

A regulation size 3 Musketeers Bar has approximately 4.3 calories per gram.

Revealing factoid: one gram of fat has 9 calories.

Educated guess based on my superior mathematical skills: a regulation size 3 Musketeers Bar has more sugar than fat.

Sources: www.sugar.com/health/gottolose.html, 3 Musketeers Bar wrapper.