As a liscensed Nutrtionist, I often have clients telling me of all the food cravings they suffer while dieting. The foods you crave, is not what your body really wants. Here is just some example of foods, and the minerals/vitmains your body may be lacking. There are tons of good books out there that actually tell you what foods to subsituite., An example would be someone craving ice cream, They may think ice cream well cure their craving, but in all reality it is omega 3 from fish that their body wants.
heres some examoles below:

Salty foods such as fries: After doing exercise or after going through stressful situation, our body gets tired and craves for salty foods because salt makes us thirsty and then we go for a drink. Check your urine, if it is dark, you are surely dehydrated. You need to drink more water for sure. Salty food cravings might also be due to adrenal fatigue which happens when you go through stressful situation. Find out the way to de-stress yourself by using relaxation techniques such as doing meditation or yoga. Sometimes, lower zinc level in your body may also make you crave for salt as lower zinc level means your taste buds is not working well and you want to boost your taste bud by eating salt or salty food.

Ice: craving for ice may suggest low haemoglobin levels in your body. In other words, your body hasn't got enough iron to produce red blood cells, finally leading to anaemia. Ice relieves pain and inflammation caused by anaemia, so you crave for it. I had very bad cravings for ice during pregnancy. I went for blood test which showed that I had low haemoglobin levels. After increasing the intake food containing high levels of iron such as red meat, spinach, iron tablets, my cravings for ice gradually vanished.

Carbohydrates such as breads, cakes and cookies: Low carbohydrate level in your body leads to mood swings. In extreme cases, it might even lead to depression. Carbohydrates raises feel-good hormone called serotonin, a neurotransmitter which helps to relax front part of the brain, so we crave for carbohydrates to boost our mood.

The other reason for such cravings might mean that your thyroid gland is either over-active or under-active. Go for low GI and wholemeal food if you crave for carbohydrates, as it will help you feel satisfied for longer period.

Chocolates and Ice creams: Cravings for chocolate means that your body is longing for magnesium, which is the mineral that gives energy to our body. Before and during menstruation the need for magnesium increases and we might crave for chocolates abnormally.

If your mood is low, you would crave for chocolates as well, because chocolate, like carbohydrate and sugar, also leads to the release of serotonin which, then, increases the level of alkaloids, mood-boosting hormone, in the body. Eating whole grain foods, leafy green veggies, nuts, seeds and legumes can help you out in this case.

Caffeine: Craving for caffeine may mean that your adrenal glands are exhausted and, as a result, you want to have caffeine to increase the energy levels in your body. It might also mean decrease in vitamin c in your body or not having enough amount of iron level in your system. Women loose iron through blood during menstruation. Iron level is also decreased during pregnancy and lactation period. As a result, they feel tired and crave for caffeine. Increase the intake of foods such as apricots, figs or raw broccoli food instead of taking too much caffeine.

Water: If you feel like drinking water all the time and your thirst never seems to go away, you are lacking in omega-3 and omega-6 fatty acids in your system, which causes dry mouth and dry skin. Thirst triggered by such cause will never be satisfied by just drinking water. Eating fish, leafy vegetables or adding chia or flaxseed in your diet can help you out.

Spicy food : It means there is thyroid imbalance or a lack of sulfur in the body and you try to satisfy yourself by eating spicy and hot foods such as curry.

Dairy foods: If you are crazy about dairy products such as milk, cheese or milk chocolate, it is because you might be addicted to the amino acids found in dairy products that works like opiates. Have you heard that if you drink a glass of milk before going to sleep, you are going to have a good sleep? That explains milk working as opium to relax our brain.

Meat: Every time when you sit down for eating, if you feel like having a big steak or juicy piece of meat in your plate, then you might be having a deficiency in vitamin B, carnitine, mineral or iron deficiency.