How do I stop other pets from eating a diet dog's portion?

A weight loss plan works on a specific, deliberately reduced calorie target, so any extra food from finishing another pet's leftovers or being given a sympathetic extra portion by mistake can meaningfully undo the intended deficit.

This is especially relevant if a faster eating housemate normally moves on to finish other bowls, a habit that might have been harmless before the diet started.

Feed pets in separate rooms with doors closed during mealtimes, or use enough physical distance and direct supervision to prevent access to each other's bowls.

Pick up all bowls promptly once each pet has finished, rather than leaving food out, which removes the opportunity for a dog to snack on leftovers later.

Make sure everyone in the household knows the diet dog's feeding plan and understands why extra food, even small amounts given out of sympathy, undermines the calorie deficit.

If children are involved in feeding or treat giving, explain simply why the diet dog needs to stick to its specific amount for now, and consider giving them an approved role, such as handing over the correctly weighed portion at mealtimes, so they still feel included in the dog's care and daily routine without undermining the plan by quietly sneaking in extra bits of food out of sympathy whenever nobody else happens to be watching them closely enough.