Well, I can understand why your mom has lost her will to try another fad diet. Who likes repeated failures? While it is true that overweight increases a person’s health risk, recent research do find that it is more hazardous to repeatedly lose then regain weight (often-called weight cycling or yo-yo dieting).
Why not talk about healthy eating, one low in fat, (for now don’t mention calories), combined with regular exercise with her doctor’s approval. Why not exercise regularly with your mom? It would be a good opportunity for quality family time and people are more likely to exercise when they have an exercise buddy who is committed. Exercise increases the “feel good me” endorphins in the brain and increases a person’s energy level. Water exercises put less strain on weight-bearing joints and are a good place to start exercising like water aerobics.
Remember, that you cannot make your mom lose weight and nagging will only increase her resistance to weight loss. Positive comments will encourage her. Reward even the smallest attempt at a healthy lifestyle.