Some people can gain weight by eating more calories than they burn.
What’s the full context? What passage are you referring to?
Answer:
During the game, Mary wanted to go to the concession stand badly; but it was too interesting to leave.
Explanation:
assuming that you just want to fix it grammatically:
add a comma after the word game because it is a dangling modifier
add a semicolon after the word badly because it separates 2 independent clauses.
