Tried different diets and exercises but i just lose weight and my skin won't tighten back up. how can i tighten my belly up again?

Metabolism: To tighten up skin that is slack after weight loss, it usually takes monumental effort when done via exercise and when the person is over 35 years of age. One of the best exercises which gives overall toning is swimming laps (repetitive anaerobic exercise). Running long distances is also helpful, but can be stressful to joints. Short of exercise, surgery might be a consideration.