My wife is 29 years. her weight is just 45 kgs ang height is 5.8. pls tell me how she can gain some weight.

Why, then how: I encourage you to work with your wife's doctor, nutritionist in that office, and a personal trainer rather than any off-the-shelf plan. Share with her doc and team the "why" about wanting to gain weight and where (on the body). Lean weights are often healthiest.Body weight is just a number, affected by many factors (e.g., bone, muscle, water, fat, etc.). Sharing 'why' will lead to a healthy plan.

If she desires.: Eat healthy foods high in calories. Eat 6 meals /day. Work on strength training to build large muscle groups. Work out w heavier weights w fewer repetitions. Sleep at least 8 - 9 hrs/night. Hydrate well w water. Foods to help w weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, avocados, granola, trail mix, dried fruits, protein shakes & bars, lean meats, poultry

See below: Agree with Dr. H. Being skinny in an other healthy person is not a cause for concern. She is likely to gain weight with increasing age and then she will look back fondly at this time when she could ear and not gain weight. You may consult this site for advise on nutrition: : http://www.choosemyplate.gov/.