The process of ageing brings about many physiological and immunological changes in your body at 40. These changes happen to a greater extent in women post menopause that leads to unwanted weight gain and drop in calcium levels. A right diet not only fuels the body with nutrients which slow down the visible effects of ageing but also prevents the onset of many chronic diseases and enhances life expectancy. Here are some diet tips and plan by well-known nutritionist Elina Dawoodani. Calorie needs The ideal BMI for the Indian population of all ages is between 18.5 kg/m2 to 22.9 kg/m2.