Creating a Safe Weight Loss Diet Plan for Your Pet

Pet obesity has reached epidemic proportions, with over 50 per cent of dogs and 60 per cent of cats classified as overweight or obese in recent veterinary surveys. Yet many owners do not recognise the problem because gradual weight gain is easy to overlook, and our perception of "normal" has shifted as heavier pets become more common.

"Owners often tell me their pet is just 'a bit chunky' or 'big-boned.' But the reality is that even 10 to 15 per cent above ideal weight significantly increases the risk of diabetes, arthritis, heart disease, and certain cancers. Helping your pet reach a healthy weight is one of the most impactful things you can do for their quality of life." — Dr. Sarah Chen, DVM

How to Assess Your Pet's Weight

• Ribs: You should be able to feel your pet's ribs with gentle pressure. If you need to press firmly, there is excess fat covering them.
• Waist: Viewed from above, your pet should have a visible waist — a narrowing behind the ribs. If they look like a sausage from above, they are carrying too much weight.
• Belly tuck: From the side, the abdomen should slope upward from the ribcage. A hanging or level belly indicates excess weight.

Your vet can assign a Body Condition Score (BCS) and calculate your pet's ideal weight. This is the essential first step before starting any weight loss programme. For a deeper look at the health risks, see our guide on obesity risks and management.

Successful pet weight loss comes down to one principle: consuming fewer calories than burned. But the calorie deficit must be moderate and carefully calculated to ensure your pet loses fat, not muscle, and does not suffer nutritional deficiencies.

The Veterinary Approach

Your vet will calculate your pet's target weight and determine a daily calorie intake designed to achieve a loss of 1 to 2 per cent of body weight per week. This is typically the Resting Energy Requirement (RER) of the target weight, not the current weight.

For example, a 15 kg dog whose ideal weight is 12 kg would be fed based on the calorie needs of a 12 kg dog: approximately 394 kcal × 1.0 = 394 kcal per day. This creates a safe calorie deficit without extreme restriction.

For Dogs

• Calculate RER at target weight: 70 × (target weight in kg)^0.75
• For weight loss, feed RER × 1.0 (no multiplier)
• Expect to reach target weight in 3 to 6 months depending on how much needs to be lost

For Cats

• Cats should never be put on a crash diet — rapid weight loss in cats can trigger hepatic lipidosis (fatty liver disease), a potentially fatal condition
• Aim for no more than 1 to 2 per cent body weight loss per week
• Typical target: 180 to 230 kcal per day for an average cat needing to lose weight
• Never reduce a cat's food intake by more than 25 per cent at once

Critical: Do not guess calorie targets. Have your vet calculate them based on an examination. What seems like a reasonable reduction could be dangerous, particularly for cats.

Once you have a calorie target, the next step is choosing how to deliver those calories in a way that keeps your pet satisfied, nourished, and healthy.

Switch to a Weight Management Formula

Veterinary weight management diets are specifically designed for calorie restriction without nutritional compromise. They are lower in fat, higher in fibre (for satiety), and fortified with vitamins and minerals to ensure your pet gets everything they need despite eating less. Simply feeding less of your current food may not provide adequate nutrition at reduced portions.

Measure Everything

Use a digital kitchen scale to weigh food portions — measuring cups are inaccurate and consistently overestimate. Studies show that owners using cups rather than scales overfeed by an average of 30 per cent. This one change alone can make or break a weight loss programme.

Eliminate Hidden Calories

• Treats should make up no more than 10 per cent of daily calories — and be counted in the daily total
• Replace high-calorie commercial treats with vegetables: carrots, green beans, cucumber, and courgette are low-calorie alternatives that most dogs enjoy
• Stop table scraps entirely during the weight loss period
• Ensure all family members are on board — one person sneaking treats can sabotage the entire plan

Increase Meal Frequency

Dividing the daily allowance into 3 or 4 smaller meals (instead of 1 or 2) helps manage hunger and maintains more stable blood sugar levels. For cats, puzzle feeders that slow eating and provide mental stimulation are particularly effective.

Diet alone can achieve weight loss, but combining calorie restriction with increased activity produces better results, preserves muscle mass, and improves overall fitness and mental health.

For Dogs

Start with whatever your dog can comfortably manage — even if that is just a 10-minute slow walk. Increase duration and intensity by 10 per cent per week. The goal for most overweight dogs is to build up to 30 to 60 minutes of moderate exercise daily.

• Walking: The foundation of any exercise programme. Increase distance before increasing pace.
• Swimming: Excellent for obese or arthritic dogs because water supports body weight. Even 5 minutes of swimming provides significant exercise.
• Play: Fetch, tug, and interactive games add variety and mental stimulation.

Avoid high-impact activities (jumping, sprinting, rough play) until your dog has lost a significant amount of weight. Excess weight places enormous stress on joints, and vigorous exercise before weight loss can cause injury.

For Cats

Indoor cats need deliberate exercise opportunities. Interactive play sessions of 10 to 15 minutes, twice daily, are ideal. Wand toys, laser pointers (ended with a catchable treat), and battery-operated moving toys all encourage movement.

Scatter-feeding — placing kibble in different locations around the house — forces cats to move between meals. Vertical spaces (cat trees, shelves) encourage climbing, which burns significantly more calories than walking on flat ground.

For breed-specific exercise ideas, see our guide on exercise requirements by breed.

Weight loss is a marathon, not a sprint. Most pets take 3 to 8 months to reach their target weight, and the journey requires regular monitoring and adjustments along the way.

Weekly Weigh-Ins

Weigh your pet at the same time of day, on the same scale, once per week. Record the number. For small pets, use a kitchen scale; for larger dogs, weigh yourself alone then holding your dog, and subtract. Many veterinary clinics offer free weigh-in visits — take advantage of these for accurate tracking.

Expected Rate of Loss

• Dogs: 1-2% of body weight per week (a 20 kg dog should lose 200-400g per week)
• Cats: 1-2% of body weight per week (a 6 kg cat should lose 60-120g per week)

If your pet is not losing weight after 2 weeks of strict adherence, reduce calories by a further 10 per cent and reassess. If they are losing faster than 2 per cent per week, increase food slightly to prevent muscle loss.

Monthly Vet Check-Ins

Schedule monthly weigh-ins with your vet during the weight loss period. They can assess body condition, adjust calorie targets, check for any health concerns, and provide encouragement. Many clinics run nurse-led weight management programmes that provide structured support and accountability.

Reaching target weight is a huge achievement, but maintaining it requires ongoing vigilance. Transition gradually to a maintenance calorie level (typically 10-20 per cent more than the weight-loss ration) and continue measuring portions. For help calculating the right maintenance amount, see our complete feeding portion guide.