system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If the situation arose and it was for survival, would I be able to live off of just water and multi-vitamins?
gpt
Dietetics student here! Your body needs what we call macronutrients, which provide you with energy in the form of calories. Your body burns anywhere between 1500 (low weight, sedentary individuals) to 3500 (high-intensity athletes) Calories a day. These are present in the diet as carbohydrates, proteins, fats, and to a small degree, alcohol.

You *can* survive on one macronutrient for an extended period of time; for example, potatoes are primarily carbohydrates. However, eliminating one macronutrient from the diet does have consequences. Protein deficiency, for example, is one of the largest nutritional concerns in third-world countries, especially in Africa. Each deficiency can lead to a variety of diseases and health concerns.

Multi-vitamins are micronutrients, and we need them – them being vitamins and minerals – to be healthy, but they do not provide any energy. In a survival situation, you'd ideally want a source of water, carbs, proteins, and fats. Most of the micronutrients can be found in the food you'd likely be eating.

**EDIT:** It's important to note that certain nutritional deficiencies can lead to eventual death on their own. However, as long as you have an adequate caloric intake, you will not die from starvation. For example, Vitamin D deficiency can lead to death in extreme cases. Same goes for B12.