Dog obesity: to lose weight, feed for the weight your dog doesn't have yet

Take a six-year-old, 30-kilogram Labrador who is always first at the bowl. You have to search for the ribs under your palm, there is a soft pad of fat over the lower back and at the base of the tail, and no waist is visible from above. He eats 362 g of dry food a day, and that portion is correct. It is precisely calculated to maintain the 30 kg he already has.

For a dog that is losing weight, the portion is calculated from the target weight, not the current one: for a 30 kg dog with a target weight of 24 kg, that is 759–911 kcal a day, or 191–229 g of food at 397 kcal/100 g instead of 362 g (calculation based on NRC 2006 and AAHA 2014). Where exactly the 24 kg comes from and why you can't simply cut the usual bowl in half, I'll show with numbers. Treats, calculated — how many calories are in a “little piece” and how much to take out of the bowl.

See also: Puppy feeding amounts by age and weight

And one figure that you have most likely seen in other articles about dog weight loss, I won't give here as a norm. I'll explain why at the end.

Why should a dog lose weight if it feels fine?

In a 14-year study of 48 Labradors, dogs that got 25% less food throughout their lives had a median lifespan 1.8 years longer, and chronic diseases, including osteoarthritis, began later in them (Kealy et al., JAVMA 2002; Lawler et al., British Journal of Nutrition 2008).

The design was simple. Puppies were split into pairs at eight weeks of age, and one dog in each pair got a quarter less food than the other for the rest of its life. The same diet, just a smaller amount.

The difference was measured in years.

The same study has a detail that moves the conversation from looks to metabolism: dogs with more than 25% body fat had insulin resistance, and it independently predicted how long a dog would live.

One clarification, so as not to credit the study with more than it shows. These dogs did not lose weight: they got the smaller portion from puppyhood. The study shows the cost of excess food in years; how to get rid of weight already gained is what we'll calculate next.

To do that, you first need to know how much your dog should weigh. And the scales won't help much here.

How can you tell if a dog is overweight?

Excess weight in a dog is assessed by hand, using the WSAVA 9-point body condition scale (Laflamme, 1997): 4–5 points is considered ideal, and 7 points means roughly 20–30% above ideal weight.

Body condition is an assessment of a dog's fat reserves by hand and by eye, without scales. The WSAVA chart describes score 7 like this: “ribs difficult to feel… fat deposits over the lumbar area and base of the tail” (our translation).

Based on the WSAVA Body Condition Score chart (Laflamme, 1997).

The Labrador from the intro falls into row “7” because he does have ribs, but you have to search for them. For 8–9 points the calculation below doesn't apply; you need a veterinarian.

And row “7” gives the target that the bowl is calculated for.

How do you calculate the daily food amount for a dog that is losing weight?

The daily amount for weight loss is calculated from the target weight in two steps: first the resting energy requirement RER = 70 × (target weight in kg)^0.75 per NRC 2006, then a multiplier of 1.0–1.2 per the AAHA 2014 guidelines.

Target weight is the dog's weight in ideal condition, at 4–5 points on the WSAVA scale. At 7 points you find it by dividing the current weight by 1.2–1.3: 30 kg gives 23–25 kg, and for the Labrador we take the middle, 24 kg. RER for 24 kg is 759 kcal.

The whole trick is in the multiplier. For maintaining a calm dog, our portion calculator uses 1.3, which is 30% more than the starting weight-loss multiplier of 1.0, and with that multiplier the weight may never budge (AAHA 2014).

The easiest option is to keep the Labrador's usual 30 kg bowl, 362 g, and hope longer walks will do the rest. A portion calculated to maintain weight does exactly that: it maintains the weight. If you calculate from 24 kg instead, the bowl holds 191–229 g, 133–171 g less every day.

Your dog is most likely in the table below too.

How many grams of food should you give a dog that is losing weight?

A dog at 7 points that is losing weight gets from 72–86 g of 397 kcal/100 g food a day at 8 kg to 237–285 g at 40 kg (calculation based on NRC 2006 and AAHA 2014).

Target rounded to 0.5 kg, maintenance calculated with a factor of 1.6. Grams are for 397 kcal/100 g food, the DELICATE energy value (metabolisable energy, calculated per NRC 2006). The amount for a healthy dog is covered in the article on food amount by weight.

After a table like this, it's tempting to simplify: cut the usual portion in half. By eye it comes out almost the same.

Why can't you just cut the portion in half?

The lower limit of the daily amount during weight loss equals the RER of the target weight, and you must not go below it even temporarily: along with the calories, vitamins and trace minerals disappear from the bowl (AAHA 2014).

For the Labrador, the floor is 759 kcal, or 191 g. Half of his usual 362 g is about 181 g.

Ten grams below the floor.

In every row of the table, the floor is about 53% of the usual portion, so half always ends up below it.

Take also a four-year-old 20 kg mixed-breed dog, also at 7 points. Half of his 267 g is about 133 g, while the floor for a 16 kg target is 141 g. The right bowl for him is 141–169 g: noticeably less than he used to eat, but not below the floor.

What's left is learning to see that the weight loss is working. That's also where the promised figure comes in.

How do you check that a dog is really losing weight?

A dog on a diet is weighed once a week before a meal, on the same scales and at the same time of day, and if the weight hasn't moved in two weeks, the portion is reduced by about 10%, but not below the RER of the target weight. The same was done in a program with 926 dogs (Flanagan et al., 2017).

The table only gives a starting point, and then the dog adapts: in the study of 48 Labradors, dogs on a restricted diet needed 17% less energy per kilogram of lean body mass (Lawler et al., 2008).

Now about the figure from the beginning. Articles keep repeating a “safe rate of 1–2% of body weight per week”. That's how laboratory dogs lost weight; pet dogs lose it more slowly.

At the University of Liverpool clinic, 143 dogs lost 0.6% of their weight per week and took a median of 200 days to slim down (German et al., 2015). For a Labrador going from 30 to 24 kg, that's 5–8 months, and that's normal.

And count the treats, because they're calories too, and with a daily allowance of 759–911 kcal they make a noticeable difference for the Labrador. What table food dogs must never have is collected in a separate dose table.

All that's left is to make a plan so the Labrador can start losing weight tomorrow.

Where do you start a dog's weight loss tomorrow?

Weight loss for a 30 kg Labrador starts with a portion of 191–229 g of food a day instead of 362 g, and after that the portion is checked against the scales.

• If your dog is at 7 points, like the Labrador from the intro, weigh out 191–229 g of food in the morning for the whole day and don't add any more.
• If after two weeks the scales still show the same 30 kg, reduce the portion by 10%: 229 g becomes 206 g. Don't go below 191 g.
• If the weight stalls even at 191 g, don't cut the bowl any further: that's a matter for a veterinarian.
• If your dog at 7 points weighs something else, divide its weight by 1.25, enter the result in the portion calculator with the “Calm” activity level, and divide the grams shown by 1.3. That's the lower limit; the upper one is 20% higher: for the Labrador the calculator will show 250 g, and 250 ÷ 1.3 gives 192 g: the same 191 g, allowing for the calculator rounding to 5 g.

The Labrador's target of 24 kg appears in this story twice: first as the number the bowl is calculated for, even though the scales don't show it yet, and later on the scales themselves, when the ribs are once again easy to find under your palm and the waist is visible from above.

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