Hello neo,
It would seem to me that your GI problems are an indication of your reduced powers of digestion and assimilation, in the sense that although you have a good diet you remain underweight. If these powers are functioning as they should, then weight gain should be quite easy with whatever foods you happen to be eating.
A sure sign of impaired and inefficient digestion is a coated tongue, even halitosis and other unmistakable symptoms, which results from the fermentataion & putrefaction of the foods within the digestive tract.
To solve this problem you will need to improve these powers of digestion & assimilation with the only sure fire method of doing so: by resting your digestive apparatus with a water-fast-conducted-according-to-thirst; this will cleanse your system of toxins and accomplish the healing that you need, and where even the most underweight person can fast quite safely for up to at least a week with only added benefit.
Some of the Benefits of Water-Fasting................
The digestive system is "rejuvenated" and becomes more effective; the peristaltic action of the intestines (the cause of a natural bowel movement) is stronger after fasting.
Fasting retrains your tasting sense back to more healthy food as acute sensitivity is restored.
Mental clarity is improved and brain fog is lifted.
Rapid, safe weight loss is achieved without flabbiness
The nervous system is balanced
Energy level and sensory perception is increased. The longer the fast, the bigger increase in energy and vitality. You normally need less sleep.
Organs are revitalized
Cellular biochemistry is harmonized
The skin becomes silky, soft, and sensitive
There is greater ease of movement
Breathing becomes fuller, freer and deeper
Fasting can increase confidence in our ability to have control over our lives and our appetite, and that our body is self-regulating and a self-healing organism capable or establishing balance when given the possibility to do so.
Normal metabolic and cell oxygenation are restored.
Detoxification - as soon as the body realizes that it's fasting it will begin to eliminate those things that cause disease, such as fat cells, arterial cholesterol plaques, mucus, tumors, and even stored up worries and emotions.
A properly combined diet post fast will also greatly enhance your digestive system, by using as little bodily energy as possible in the process, and radically reduce your tendency to putrefy and ferment the foods you have eaten.
Digestion is far more efficient as a result..........
http://chetday.com/fcnecess.html
Regards
Chrisb1.