I'm not sure if this first one is a compliment or not, but here you go:

• Elle est grande et forte mais féminine.
  She's big and strong, but feminine 

These next ones definitely aren't positive!:

• Il a beaucoup vieillit ces temps-ci.
  He's aged a lot recently. 
• Il a perdu tous ses cheveux.
  He's lost all his hair.

Hopefully, they'll say this about me when I'm older:

• Avec l'âge, Jean a plus de charme, beaucoup plus que quand il était jeune. 
  Juan has got more attractive as he's got older. He wasn't so attractive when he was young.

These next couple of sentences are also much more positive: 

• Elle a les cheveux blonds et une jolie frange.
  She has blonde hair and a cute fringe.
• Il est costaud et a de grands yeux bleus.
  He's well-built and has big blue eyes. 

Now, let's not get bitchy!:

• Elle était plus jolie avec les cheveux longs. Depuis qu'elle les a coupé, elle a perdu tout son charme*
  She was prettier with long hair. Since she had it cut she's much less attractive.

Here's the literal translation:

* elle a perdu tout son charme = She's lost all her charm

• Quand elle était jeune elle était très mince et avait les cheveux longs.
  When she was young she was very slim and had long hair.
• Je trouve que tu as beaucoup changé. Tu as perdu beaucoup de poids non ?
  You seem to have changed a lot. You've lost a lot of weight, haven't you? 

Personally, I'm always up for more nosh:

• Tu dois manger, tu es trop maigre!
  You need to eat! You're really skinny!

Let's look at some more expressions for physical appearance:

• Il est de petite taille et a un beau sourire, avec de grandes dents blanches.
  He's short and has a nice smile with big white teeth. 
• Elle est rondelette, avec de magnifiques cheveux frisés.
  She's chubby with lovely curly hair. 
• Cette fille a de belles jambes, longues et musclées. 
  That girl has beautiful long, muscular legs.
• Il a des jambes bien fuselées et des abdominaux bien marqués.
  He's got toned legs and well-defined stomach muscles. 

There's hope for us all:

• Elle a tonifié son corps en 3 mois...elle n'était pas très en forme avant.
  She's toned her body in three months. She wasn't in shape before.
• Quel bel homme ! Il est très masculin.
  What a good-looking man! He's very masculine.

Sometimes you just can't have it all:

• C'est un jeune garçon roux, avec des taches de rousseurs.
  He's young and ginger-haired, with freckles.
• Elle a toujours nié avoir eu recours à la chirurgie esthétique
  She has always denied having had cosmetic surgery.

Some other stuff here