aevens emphasized the fact that there is a wealth of info on this website.. Everytime you ask this you hear the same response.. is the same for us when we see the question its the same as the other 3000 and we must state the samething everytime.
If your mother is asking you for advice.. I would highly recommend her to see a nutritionist. Here is a short list of bad versus good foods
Bad: Fast food, pop/soda, candy, snacks.. pretty self explanatory
Good: lean red meats, chicken(not KFC), veggies, fish, FISH(tuna mm), eggwhites(protein), sweet potato and brown rice(good carbs) fruits, olive oil(good fat, but don't kill the oil thinking its good.)
A sufficient amount of carbs, fat, and protein is nec. for her. Must eat fat to lose fat.. but healthy good fat/carbs. If she is serious tell her to go onto and track her caloric intake.
For future questions- saying your mom is not fat, but chubby gives us nothing to start with at all. Age, weight, height, her diet now... her activities now are essential for a good response. We know she's a mom and a female. Thats for diet... she needs to get active.. start walking. She needs to know diet is 80-85% of he success.. but exercise is ESSENTIAL for it to work together right. Hope this helped.