Hi,
I'm sorry, I don't have the time to read all the previous comments so I may well just be repeating some of the excellent advice I've already seen on a skim read.
Firstly, well done for acknowledging it, it can be really hard for owners to see their own dogs as carrying excess weight (1), and even when vets point it out 50% of owners will disagree with their diagnosis. So well done for getting over the hardest hurdle of recognising the issue and wanting to do something about it! Someone mentioned above that overweight labs live on average 2 years shorter lives than healthy weight counterparts, what they didn't mention is that that's being only 10% overweight, so getting your dog's weight down whilst he's still young will be so beneficial for both his health, quality of life and length of life! (3, 4, 5).
So there's a few key things to know when approaching weight reduction.
Firstly, diet has way more impact on reducing weight that increasing exercise does (6). This is because for exercise to have a real impact on weight it needs to be a lot of vigorous activity, which generally severely overweight dogs are not able to do. (That's not to say exercise isn't still valuable, it won't help much with shifting weight but it will help to keep him toned which helps protect joints and makes weight management easier long term. I just wouldn't focus on it too much for now, if he's getting some lead walks that will be fine for now to help keep him toned, you don't want to overdo it whilst he's got extra strain on his joints)
Secondly, you can feed less than the recommended amount on pet food bags. So there's a few issues with the food quantity recommendations. Firstly, they don't take into account the dog's current weight status, they just say if your dog currently weighs 60kg feed him X amount, which is going to be far too much for a lab that's above his ideal weight. And even the recommended ranges for his target weight can't possible take into account all of the nuances that effect a dog's calorie requirement (age, sex, neuter status, activity levels, current BCS, metabolism). So don't feel you have to stick within what the bag recommends!!
In terms of deciding how much to feed there are a few options;
You can use formal calculations, or ask your vet to, for a neutered male the best guess for weight reduction is to feed 70% of the calorie requirement that would keep him a stable weight. This can be calculated using
70 X ( ideal weight (kg) ) ^ 0.75. In other words, his ideal weight in Kg to the power of 0.75, then times by 70, this gives you the number of calories he'll need a day. You can then work out how many grams a food if your food has the Kcal per g on the packet. Some packets don't have this information on but it can be estimated using this calculator www.pfma.org.uk/dog-calorie-calculator-nrc-method
OR, an easier alternative is to reduce what you're currently feeding by 25% to start with. Weigh what you're currently feeding, work out 75% of this, and weigh his food every day. If he's on kibble, weigh it out in the morning and all his meals and rewards can come out of that.
* One thing to be aware of though, is that normal (complete, balanced) dog foods allow a window so you can feed them ~80% less than what would keep them a steady weight whilst still providing all of the essential nutrients and vitamins in the necessary quantities. If you are going to reduce his food to less than 80% of his maintenance calorie requirement, I highly recommend swapping to a weight reduction formulated diet (e.g., royal canin satiety or hills weight reduction). These allow you to feel much less calories whilst still providing all of the essential nutrients. They're also high in fibre to help keep him feeling full.
Keep weighing him regularly (which your doggy fat club) will help with, and you can then easily track whether the reduction in food is having the desired effect.
In terms of treats, not all fruit/veg are actually all that low in calories, some are surprisingly sugary. I would stick to green veggies (broccoli, cabbage, courgette, cucumber, green beans, celery). Do little taste tests by offering two foods in a closed hand, let him sniff both and see which he goes back to, so you can find out which are his favourites. Also, think about no-calorie treat options, make a list of things that he enjoys doing and that way if you ever feel bad that he's not getting food treats you can make sure he's still a happy boy getting to do/experience things he does enjoy.
And in terms of helping to keep him full if you feel concerned that reducing his meals is going to make him hungry/unhappy, there are a few key things you can do. Slowing meals down helps increase satiety because it takes roughly 10 minutes from when dogs start eating for their brain to start sending out the hormones that tell their body they're not longer hungry. So if he gobbles down his meals and then still seems hungry, use slow feeders, puzzles, scatter feeding, scent games, snuffle mats, kong wobblers, treat balls, any type of enrichment that will slow down his meals.
You can also bulk out his meals using the low-calorie veg mentioned above or by soaking his kibble until it expands. The weight reduction formulated diets are brilliant because they're already sort of bulked out with the extra fibre so the portion size probably won't appear to change much even though it will contain a lot less calories.
Healthy weight reduction would be roughly 0.5% to 2% of his starting body weight each week (300g to 1200g a week for him), it will take a while to get him down to his ideal weight healthily, don't get disheartened though, by the time he loses 6% of his SBW (gets to 56.4kg) you should start to notice positive changes in his mobility and well-being. Take photos and videos at the start and along the journey so that any time you're feeling disheartened you can look back at the progress you have made and the positive impact it's had on him!
Over the last year I helped my dog lose 50% of his starting body weight, so a very similar situation to yourself, the best thing I found that helped is to make a table with the headings: date, amount fed, weight/measurements. And each day I recorded how much he was fed, every few days to start off with we weighed him and measured around his ribs and waist (which might be an easier thing for you to keep track of at home, my dog is a chihuahua so weighed him on the kitchen scales). Keeping track of that I could quickly see if he was still losing weight and knew how much food I'd been feeding him recently so I could easily drop it by 10% at times he stopped losing weight. I've attached some photos of him, he went from 4.5kg to 2.2kg and he was like a different dog, before he couldn't play with his sister because he couldn't run after her, he couldn't climb stairs, now he zooms around the garden, flies up the stairs and can easily jump onto the sofa to find himself the sunniest spot for a snooze.
Would love to hear updates on how he's getting on if you're willing to keep us posted!
Best of luck and apologies for the essay, it's just something I know a lot about (I'm a welfare scientist currently researching canine obesity) and want to help others get the same results my dog's had :)
(1) - Eastland-Jones, Rebekah C., et al. "Owner misperception of canine body condition persists despite use of a body condition score chart." Journal of nutritional science 3 (2014).
(2) - White, G. A., et al. "Canine obesity: is there a difference between veterinarian and owner perception?." Journal of Small Animal Practice 52.12 (2011): 622-626.
(3) - Kealy, Richard D., et al. "Effects of diet restriction on life span and age-related changes in dogs." Journal of the American Veterinary Medical Association 220.9 (2002): 1315-1320.
(4) - German, A. J., et al. "Quality of life is reduced in obese dogs but improves after successful weight loss." The Veterinary Journal 192.3 (2012): 428-434.
(5) - Kipperman, Barry S., and Alexander J. German. "The responsibility of veterinarians to address companion animal obesity." Animals 8.9 (2018): 143.
(6) - Chapman, Melanie, et al. "An open-label randomised clinical trial to compare the efficacy of dietary caloric restriction and physical activity for weight loss in overweight pet dogs." The Veterinary Journal 243 (2019): 65-73.