Dietetics: what dietitians do, conditions they help with and what to expect

Dietetics is the clinical use of food and nutrition to prevent and treat disease. The British Dietetic Association describes dietitians as qualified health professionals who assess, diagnose and treat dietary and nutritional problems at an individual and wider public health level, and who work with both healthy and sick people. They translate research on food, health and disease into practical guidance on what to eat and drink.

In practice that can mean planning enteral feeding for someone who cannot swallow safely, adjusting carbohydrate intake for a person with diabetes, managing a restricted diet for coeliac disease, supporting weight loss before surgery, or helping a family whose child has severe food allergy keep growth on track. Dietitians work in hospitals, community services, private practice, sport, public health and industry.

The BDA explains that dietitians are the only nutrition profession with statutory regulation: the title is protected and registration with the HCPC is a legal requirement. Their education involves an accredited degree or apprenticeship with 1,000 hours of practice placement. Registered nutritionists are a separate group, listed on the UK Voluntary Register of Nutritionists, who study accredited nutrition science degrees and need three or more years of experience evidenced by a portfolio, with no compulsory on-the-job training.

Both roles can be evidence-based and valuable, but they are not interchangeable. If you need diagnosis and treatment of a medical condition, a registered dietitian is the appropriate professional. You can check someone's HCPC registration online before booking, and the BDA has a page explaining how to do it. Titles such as nutritional therapist or nutrition coach are not protected in the same way.

The BDA lists reasons to see a dietitian: regaining weight after illness or because of a medical condition, losing weight safely, food allergy or intolerance symptoms, feeding problems in a baby or child, digestive problems or coeliac disease, and a diagnosis such as diabetes, high blood pressure or cardiovascular disease. The following are the groups most seen in outpatient clinics.

• Overweight and obesity: the NHS says a BMI of 25 to 29.9 is overweight and 30 or more is obese for most adults, with lower thresholds for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background.

• Type 2 diabetes and prediabetes: meal planning, carbohydrate awareness and weight change, usually alongside the diabetes team.

• Food intolerance: the NHS says a GP may refer to a dietitian when intolerance is suspected, and describes an exclusion diet followed by reintroduction, blood tests or a breath test for lactose intolerance as ways to investigate.

• Irritable bowel syndrome, inflammatory bowel disease and coeliac disease, where structured dietary approaches may be part of treatment.

• Cholesterol, blood pressure and heart disease, where food patterns are one lever alongside medicines.

• Malnutrition, frailty and swallowing problems, including in older adults and after stroke or surgery.

The NHS says that losing even a small amount of weight, 5 to 10% of body weight, can improve health, and suggests steady loss of about 0.5 to 1kg a week through eating fewer calories than the body uses and being more active. It describes weight loss medicines, including GLP-1 and GIP agonists such as semaglutide and tirzepatide, as usually prescribed alongside diet and lifestyle advice, with support offered after stopping to help maintain weight.

It also describes weight loss surgery for people with a BMI of 40 or over, or 35 or over with other conditions that could improve with weight loss, with lower thresholds for some ethnic groups, and notes regular check-ups for 2 years afterwards. A dietitian is usually central before and after surgery, helping with portion size, protein, vitamin supplements and avoiding regain. Prescription medicines are decided by a prescriber, not the dietitian, who supports the eating pattern that goes with them.

Dietitians rely on food and symptom diaries, measurements such as weight, height and sometimes waist, blood tests ordered by the medical team, and structured dietary assessment. Body composition analysis and gut microbiome tests are sold directly to consumers; their clinical value varies, and results should be discussed with a clinician before changing your diet.

The NHS is direct about commercial food intolerance kits: some tests that claim to diagnose intolerances are not recommended because there is limited evidence they give accurate results, and they may suggest avoiding multiple foods, which can be harmful. If you have already had one, take the report along but expect a dietitian to start from your symptoms.

The BDA says that to see an NHS dietitian you tell your GP practice that you would like to see one. In many areas there are also community weight management services, and the NHS says you can find them via your integrated care board, GP website or reception. Hospital dietitians usually see inpatients and people referred by specialists such as gastroenterologists, diabetologists and surgeons. The 18-week referral standard applies to many hospital pathways; community dietetic waits vary widely.

Privately, you can usually refer yourself to a dietitian without a GP letter. Check HCPC registration, ask about experience in your condition and whether they work with your GP or specialist. What shapes cost is the length of the first appointment, the number of follow-ups, whether a meal plan or written report is included, and whether remote appointments are offered. Insurers sometimes cover dietetics only when part of a specialist pathway, so check before booking.

A first appointment usually covers medical history, medicines, usual eating pattern, appetite, weight changes, lifestyle and goals. A three-day food and symptom diary is often requested beforehand.

• Bring recent blood tests, clinic letters and a list of supplements.

• Write down foods you avoid and why, including any reactions.

• Ask what the realistic first goal is and how progress will be measured.

• Ask how many follow-up appointments are likely, and how to reach the service between visits.

• For a child, bring growth charts and ask how growth will be monitored.