Short answer — both veterinary (prescription) and regular retail dog‑food labels in Australia make “weight management” / “light” formulas. Common brands you’ll find here include:

Veterinary / prescription weight‑loss diets (vet recommended / often vet‑only)

• Hill’s Prescription Diet — Metabolic, r/d (weight‑loss / weight‑maintenance formulas). (hillspet.com.au)
• Royal Canin (vet products) — Satiety / Satiety Weight Management (veterinary exclusive). (royalcanin.com)
• Purina Pro Plan Veterinary Diets — OM (Overweight Management). (purina.com.au)

Over‑the‑counter / retail “light” or healthy‑weight formulas (available through pet shops / online)

• Hill’s Science Diet — Perfect/Adult “Perfect Weight” / Healthy Weight lines. (hillspet.com.au)
• Royal Canin — Light / Light Weight Care (mini/medium/maxi Light formulas). (royalcanin.com)
• Purina (PURINA ONE Healthy Weight; Purina Pro Plan retail lines and Purina ONE Healthy Weight). (purina.com.au)
• Eukanuba — Fit Body / Weight Control (light/fat‑reduced formulas). (eukanuba.com)
• Black Hawk — Healthy Benefits Weight Management (Australian brand). (blackhawkpetcare.com.au)
• Advance — Healthy Weight / Weight Control (Australian manufactured lines). (vetproductsdirect.com.au)
• Nutrience — Nutrience Care Weight Management (dry/wet weight management formulas). (nutrience.com)
• IAMS — ProActive Health / Healthy Weight formulas (weight control variants). (petstoretoyourdoor.com.au)

Notes and tips

• “Prescription” or “veterinary” formulas (Hill’s Prescription Diet, Royal Canin Vet products, Purina Pro Plan Veterinary Diets, etc.) are intended for use under veterinary guidance and may be sold only via clinics or authorised retailers — check the product page or ask your vet. (hillspet.com.au)
• Many retail “light/healthy weight” products are suitable for mildly overweight dogs but for moderate/severe obesity or if there are health problems (diabetes, joint disease, etc.) a vet diet and veterinary supervision are recommended. (Manufacturers commonly advise consulting your veterinarian.) (hillspet.com.au)

If you’d like, I can:

• list nearby vets/shops that stock any of the specific formulas above (I’ll need your suburb/postcode), or
• compare macronutrient/calorie numbers (kcal/kg, protein/fat/fibre) for 2–3 specific products you’re considering.