Question: Can you tell me the smallest healthy diet?

Robert Hampson answered on 17 Nov 2014:

I’m assuming that you mean the diet which contains everything you need to be healthy without anything that is not required for health.

Protein is required – you can find this in meat. However, meat is not required in a minimal diet as you can find all the necessary protein and amino acids in nuts, pulses and other vegetarian stuff. You require some protein building blocks called essential amino acids which your body cannot make, you need to eat food which provides them. Meat is the easiest way to get them and it means you don’t have to do careful diet planning. If you are trying to get them from nuts and stuff, its often quite difficult, you may need some supplements to get all the amino acids required. You don’t need any more than 1 serving of meat a week.
Carbohydrates are required – complex carbohydrates are best. Unrefined things like brown rice, potatoes, etc. can be good here. Refined sugar like sweets or cake are not required.
Fats/Oils – These are required to make many parts of your metabolism function, there are some things called essential fatty acids which your body cannot make but are required to function. The best source is probably small amounts of fish, but you can also get them from things like nuts or small amounts olive oil. Highly processed fats like margarine, microwave meals, pizza, cheese, etc. aren’t great.
Vitamins & Minerals – You need a full complement of vitamins and minerals, eating a wide variety of vegetables can normally provide this. You should probably eat the occasional citrus fruit to provide Vitamin C but most sweet fruits contain more sugar than is really necessary. Easiest way to get calcium (which is vital for young people) is milk or dairy products. Iron is also a priority especially for women, dark green veg is full of iron.
Fibre – You need stuff that is fairly indigestible for your bowel to squeeze on to help keep your insides moving. Things like whole bran, and again things like brown rice, etc. are good here.
Water – Absolutely vital to any diet. You need to ingest enough of this stuff to keep you health. You can get a lot as part of your food but really you need to drink at least 3 or 4 cups of liquid per day as well as the water you get from food.
Calories – You need to eat enough food in terms of chemical energy per day to keep your body running. For adult male with an average office job, the government recommends 2500 calories a day, it is 2000 a day for an equivalent adult female. If you are more active than an office worker, you need more calories.
Salt – You actually need some salt to function. Most people get too much salt from a normal diet so its not normally something to worry about needing to eat more of. Generally reducing your salt intake is a good idea. Excess salt can cause many health problems so avoid it.