Weight gain should always be in the form of muscle, not fat. If you think you're too thin and want to gain weight, don't just stuff yourself with food, especially high fat foods. To build muscle, start a weight-bearing exercise program and make healthy food choices. Exercise is key to having a healthy body. Learn how to add muscle and strength to your arms and legs. Learn how to do a safe weight training and exercise program from a certified exercise instructor at a gym or in your home. Underweight older people look and feel frail because they have lost a high percentage of their muscles. People who are inactive, whether young or old, will lose muscle mass. Loss of muscle means loss of strength. Frail people are often unable to carry out daily activities such as climbing stairs or lifting a bag of groceries. Adding pounds of fat instead of muscle to a weak, frail body will not improve strength and will put the person's health at greater risk. As your body adapts to exercise, your appetite will adapt to meet your needs. Adults need a minimum of 1 gram of protein for every kilogram of body weight per day to keep from slowly breaking down their own tissues. That is about 8 grams of protein for every 20 pounds ( 9.07 kilograms) of weight. As you gain muscle through an exercise program your appetite will probably increase and you may eat more without any conscious effort. Make healthy, low fat food choices that include plenty of lean meat, fish, beans, whole grains, fruits, and vegetables. If you have lost a lot of weight due to a temporary illness, in time, you will recover your appetite and gradually return to your normal weight without having to overeat. Serious illness can cause weight loss with muscle mass and leave the person wanting or needing to gain back healthy muscle. If weight loss is unexplained, report this to your healthcare provider. Anyone needing to gain weight following a serious illness or surgery should follow the diet and exercise recommendations given by their healthcare provider. <script><!-- D(["mb","\u003c/p\>\n\u003cp\>Be sure to get a medical checkup before you start any exercise program. If you have a serious medical problem such as heart or lung disease, work with a certified exercise leader who will prescribe a proper and safe workout program for your health condition.\n\u003c/p\>\u003c/div\>\u003c/div\>\n\u003cdiv\>Regards,\u003cbr\>Karthikeyan\u003c/div\>\n",0] ); D(["ce"]); //--></script> Be sure to get a medical checkup before you start any exercise program. If you have a serious medical problem such as heart or lung disease, work with a certified exercise leader who will prescribe a proper and safe workout program for your health condition.