Which lens and angle for subject not to look fat?

I have a subject who wants some portraits done but is very concerned with not looking 'fat'.

If I shoot it with an 85mm lens, will that solve that problem? Also, what angles tend to make people look slim? Should I shoot it from higher than eye level for example?

I also have a 135mm lens but I think that would make me have to get too far back since the subject wants mid length shots and not just headshots so I'm thinking of using the 85mm.