Obesity — NZ Condition Guide | KiwiMeds

What is Obesity?

Obesity is defined as excess body fat that presents a risk to health. It is typically measured using BMI (body mass index — weight in kg divided by height in metres squared). A BMI of 30 or above is classified as obese. New Zealand has one of the highest obesity rates in the world — around 32% of adults are obese, and rates are highest among Māori (48%) and Pacific peoples (67%).

Overview

Obesity increases the risk of type 2 diabetes, cardiovascular disease, sleep apnoea, osteoarthritis, certain cancers, fatty liver disease, and mental health conditions. It is a complex condition influenced by genetics, hormones, environment, sleep, medications, and psychological factors — it is not simply a matter of willpower. Healthy eating and physical activity remain the foundation of management, but they are more difficult in an “obesogenic environment” of cheap, ultra-processed food and sedentary work.

Treatment in New Zealand

Weight management treatment is stepped. Lifestyle interventions (dietary change, physical activity, behavioural support) are first-line and can be supported by GPs, dietitians, and the Green Prescription. Pharmacotherapy: orlistat (reduces fat absorption — funded by Pharmac for eligible patients) is modestly effective. Semaglutide (Ozempic/Wegovy) and tirzepatide (Mounjaro) are highly effective GLP-1 receptor agonists but are not currently funded for weight loss in NZ (semaglutide is funded for type 2 diabetes). Bariatric surgery (gastric sleeve, gastric bypass) is the most effective long-term treatment for severe obesity and is available in the public system for eligible patients.

NZ-Specific Information

Weight management services are available through some DHBs. The NZ Obesity Society and Obesity Action Coalition advocate for better access to treatment. The Green Prescription offers free support from a health professional for physical activity.

Frequently Asked Questions

Is obesity a disease? Yes — major health organisations including the Obesity Society and AMA classify obesity as a chronic disease requiring medical treatment. Is bariatric surgery available in the public system? Yes, for eligible patients with severe obesity (BMI ≥40, or ≥35 with significant comorbidities) who have not succeeded with other treatments.

Supplements That May Support Management

⚠️ Important: The supplements listed below have varying levels of clinical evidence. They are not a substitute for prescribed medications and should only be considered as adjunctive support under the guidance of a qualified healthcare professional. Always inform your GP or pharmacist before commencing any supplement, as interactions with prescribed medicines are possible.

• Vitamin D — Vitamin D deficiency is highly prevalent in obesity as vitamin D is sequestered in adipose tissue. Supplementation improves metabolic parameters including insulin sensitivity and may support weight management outcomes, though it does not independently cause weight loss.
• Protein Supplementation — Adequate dietary protein (1.2–1.6 g/kg/day) is fundamental to obesity management, supporting satiety, lean muscle mass preservation during energy restriction, and thermogenic metabolic effects. Protein supplements (whey, plant protein) may help achieve targets when dietary protein is insufficient.
• Glucomannan (Konjac Fibre) — A highly viscous soluble fibre that expands in the stomach, promoting satiety. At 1 g three times daily before meals, glucomannan has demonstrated modest but significant reductions in body weight, total cholesterol, and blood glucose in randomised trials.
• Green Tea Extract (EGCG with caffeine) — Green tea catechins combined with caffeine have demonstrated modest increases in fat oxidation and metabolic rate, with meta-analyses supporting small (0.5–1 kg) additional weight loss compared to placebo over 12 weeks. Effects are modest and should be considered as a minor adjunct only.
• Berberine — Berberine activates AMPK (mimicking exercise), improving insulin sensitivity, lipid profiles, and demonstrating modest weight reduction in clinical trials — mechanistically similar to metformin.

Relevant Vaccinations

Individuals living with obesity may benefit from the following vaccinations. Please discuss your vaccination status with your GP or practice nurse, as eligibility and funding through the New Zealand National Immunisation Schedule may apply.

• Influenza (annual) — Obesity is an independent risk factor for severe influenza complications. Annual vaccination is funded and strongly recommended.
• COVID-19 — Obesity is among the strongest risk factors for severe COVID-19, including ICU admission and death. Maintaining up-to-date COVID-19 vaccination is strongly recommended.
• Pneumococcal — Obesity increases susceptibility to respiratory infections. Pneumococcal vaccination is recommended.

Dietary Guidance

Evidence-based dietary modifications play a meaningful role in the management of obesity. The following foods are generally recommended as part of a balanced, condition-appropriate diet. A referral to a registered dietitian may be beneficial for personalised nutritional planning.

• High-protein dietary pattern (lean meat, fish, eggs, legumes) — Protein is the most satiating macronutrient and has the highest thermic effect of feeding (20–30%). High-protein dietary patterns reduce appetite, preserve muscle mass during energy restriction, and support metabolic rate.
• High-fibre foods (vegetables, legumes, whole grains) — Fibre promotes satiety through multiple mechanisms (gastric distension, GLP-1 release, microbiome fermentation). High-fibre diets are consistently associated with better weight maintenance outcomes.
• Whole, minimally processed foods — Replacing ultra-processed foods with whole food equivalents is associated with reduced total caloric intake (by 500+ kcal/day in one clinical trial), independent of conscious calorie counting.
• Water before and with meals — Drinking 500 ml water 30 minutes before meals has demonstrated reduced meal caloric intake and enhanced weight loss in randomised trials.
• Limit: ultra-processed foods, sugar-sweetened beverages, alcohol — These are the highest-caloric-density, lowest-satiety foods. Sugar-sweetened beverage restriction alone produces meaningful weight loss outcomes. Ultra-processed foods are engineered to override satiety signalling.

Related Conditions & Medications

Related conditions: Type 2 Diabetes, Hypertension, Sleep Disorders.