A gastroenterologist is a specialist in diagnosis and treatment of conditions involving the digestive/gastrointestinal (GI) tract. These doctors are experts on how food moves through the digestive system and is chemically broken down, with nutrients being absorbed and waste excreted. You might see this kind of doctor if you are experiencing any number of stomach issues, some of which might be severe diarrhea, irritable bowel syndrome, hemorrhoids, ulcers, acid reflux, Crohn's disease and more.

An internist is a physician who focuses on the diagnosis and treatment of conditions that affect the adult population—both acute and chronic.
These doctors are often who adults see as their primary physicians because they treat a broad range of illnesses that do not require surgical or specialist interventions. They also work to help a patient maintain optimal health in order to prevent the onset of disease.
In addition to treating the common cold and flu, internists also treat chronic diseases like diabetes and heart disease.

Bariatric medicine focuses on the causes, prevention and treatment of obesity. Bariatric specialists are trained in medically supervised weight loss and the management of obesity as a chronic condition. These specialists are skilled in various disciplines that help patients lose weight and obtain optimal health.
The field encompasses dieting, exercise and behavioral therapy, anti-obesity medication, pharmacotherapy and surgery. Bariatric specialists might be from surgical backgrounds and perform obesity-related operations or they might be nutrition and hormone focused, prescribing diet and exercise plans as well as weight loss medications.
Patients defined as obese or having unhealthy Body Mass Indices (BMI) have much greater risk of heart disease, diabetes, asthma, sleep apnea, hypertension, many types of cancer and chronic musculoskeletal problems.
One subspecialty of bariatrics is the focus on the correlation between obesity and mortality.

Colorectal surgeons are doctors who perform surgery in order to correct problems with the anus, rectum or colon. These physicians perform colonoscopies, and other diagnostic procedures, in order to identify any issues that require surgical intervention. They then determine what type of surgical procedure would be best. The specialists also care for these patients post-operation to ensure proper healing and recovery.