Though obesity and acne do not involve DNA, but obesity may be related to gene type sometimes and Acne as well may be related if oily skin is the case.
But still they involve physical structure and so spells may not be helpful. I suggest you to use natural herbs and other methods to treat acne. Avoiding spicy and oily food may be helpful. I read somewhere that if you apply toothpaste on the acne overnight, it will cause it to shrink and heal, because of its ingredients. Herbs like Aloe Vera, neem etc also helps. A spell will not help in such cases.
As for obesity, why not maintain a healthy diet? Drink lots of water and exercise regularly. A spell will not be of much use without physical labour.
The last key is to believe. Along with all these methods, you should believe in yourself and have a strong will. With a healthy body and state of mind, all these are curable.