Which supplement(s) is (are) used for malnutrition depends on the type of malnutrition.
Supplements are often a part of the treatment of undernutrition. While the main focus of treatment is improving nutrition through dietary interventions, increasing caloric and micronutrient intake can be difficult through diet alone. Supplements can make it easier to take in more calories, such as using meal replacement shakes to increase calorie intake. Taking oral supplements can help to treat specific vitamin or mineral deficiencies, such as calcium, vitamin C, or vitamin B12. Zinc has also been shown to increase appetite rapidly in people with zinc deficiency and could be an option in people with malnutrition.[1][2][3] In more severe cases, malnutrition might be treated in a hospital and involve tube feeding, ongoing supplementation through an intravenous line, and regular monitoring of blood tests and body weight.[4][5]
In overweight and obesity, supplements are sometimes helpful as well. Using whey protein can help increase protein intake without adding a lot of extra calories. People with overweight or obesity can also have micronutrient deficiencies that can be replaced through vitamin and mineral supplementation. There are very few supplements that have a significant effect on weight loss. Weight-loss supplements often contain ephedrine, caffeine, and green tea extract. These may reduce appetite and assist with weight loss but can also have significant side effects, and weight-loss benefits tend to be small.[6][7][8] Weight-loss supplements are not usually part of the initial treatment for overnutrition.[9]