Resposta curta para isso é não. Mudanças metamórficas são mudanças cosméticas. Embora nunca seja explicitamente declarado.
O Metamorphmagus é uma bruxa ou bruxo com a capacidade de mudar sua aparência física à vontade.
“I’m a Metamorphmagus,” she said, looking back at her reflection and turning her head so that she could see her hair from all directions. “It means I can change my appearance at will,” she added, spotting Harry’s puzzled expression in the mirror behind her. “I was born one. I got top marks in Concealment and Disguise during Auror training without any study at all, it was great.”
Harry Potter and the Order of the Phoenix, Chapter 3, The Advance Guard
É strongmente sugerido que Metamorphmagus é semelhante a tomar Poção Polyjuice.
“Can you learn how to be a Metamorphmagus?” Harry asked her, straightening up, completely forgetting about packing.
“Well, you’ll have to learn the hard way, I’m afraid,” said Tonks. “Metamorphmagi are really rare, they’re born, not made. Most wizards need to use a wand, or potions, to change their appearance. But we’ve got to get going, Harry, we’re supposed to be packing,” she added guiltily, looking around at all the mess on the floor.
Harry Potter and the Order of the Phoenix, Chapter 3, The Advance Guard
Altera apenas a aparência física, por isso, se você é realmente velho e muda sua aparência para alguém mais jovem. Você parecerá mais jovem, mas ainda se sentirá velho.