Hello, I understand your concern. Fast food or junk food are high in fat .It is rich in Sodium and sugar which can lead to obesity and other health problems like diabetes, heart disease and arthritis. This junk food does not contain the nutrients your body needs to stay healthy. As a result, you may feel chronically fatigued and lack the energy you need to complete daily tasks. The high levels of sugar in junk food puts your metabolism under stress. When you eat refined sugar, your pancreas secretes high amount of insulin to prevent a dangerous spike in blood sugar levels. Because fast food and junk food do not contain adequate amount of protein and good carbohydrates, your blood sugar levels will drop suddenly after eating, leaving you grumpy, fatigued and craving sugar. Junk food contain large amount of fat which accumulates in your body, which causes gain in the weight and obesity .The more weight you gain, the more you will be at risk for serious chronic illness such as diabetes, heart disease and arthritis. It can also lead to hypertension. Excessive dietary sodium can also have a negative effect on renal function, even leading to kidney disease. High levels of dietary fat lead to poor cognitive performance. You will feel tired and have trouble concentrating because your body might not be getting enough oxygen. I would suggest you to get a complete evaluation and blood tests and review the reports with the physician for further management. Thank you.