Hi, I am 30 years old. My problem is from last few...

wieght loss
first of all unexplained weight loss has many causes, medical and nonmedical
Often, a combination of things results in a general decline in your health and a related weight loss. Sometimes a specific cause isn't found
  so now we must researh about the medical usese to except it and we need good histtory like   Changes in diet or appetite and Changes in sense of smell and Changes in sense of taste
and ask about life style if you sport programm and ask if ther is loss aof appetit and if there is vo 
roblems with the intestines can mean your body is not properly absorbing the food you are eating. Even if you are consuming a lot, you could suffer from malnutrition and not be able to gain weight. These types of diseases are known as "malabsorption syndromes." Some common forms of this disease type are irritable bowel syndrome, Crohn's disease, ulcers and celiac disease, according to the Mayo Clinic. Symptom can include blood in the stool, abnormal bowel movements, fatigue, pain in the abdomen, gas and possible weight loss. If you are experiencing these symptoms along with no weight gain, consult a doctor for proper diagnosis
Other, less-common, issues that could be at fault.s Some prescription medications can increase your metabolism, which will burn more calories. Cancer, infection and neurological issues can all affect your weight, usually in the form of weight loss
investigation
good medical history and good clincal history epecailly the abdomen and make mant lab history like cbc and  Monitoring your daily caloric expenditure and intake can help determine if this is the case
Causes loss of weight
Hyperthyroidism
Diabetes
Gastrointestinal IssuesP
Advice
It's best to consult a doctor to get a proper diagnosis