What you’re describing is called resource guarding, and there are a few things that you can do:
(1) Allow time for your dog to decompress after arriving at your home
A new home is a HUGE event for any dog, and it’s important to give your dog time to decompress. We recommend minimizing the presence of visitors until your dog’s a bit more comfortable and you’re more familiar with his personality and body language.
(2) Use counter-conditioning techniques to help your dog feel better about new people
Since your dog’s behavior only occurs with new people, we can infer that they have anxiety and mistrust associated with new people. To help them feel better about new people, always meet new people outside of your home and have them provide delicious items to your immediately upon arrival. For instance, you can keep a bag of treats outside of your door or instruct your friends to bring hot dog bits with them. Then, when they see your dog, have them throw pieces of the food in your dog’s general direction. This will help your dog associate new people with good things, and ultimately reduce the fear / anxiety driving his feeling of needing to guard food in the presence of strangers.
(3) Create separation between your dog and the area / thing they want to guard when new people are over.
Create a safe space for Kai to go when visitors are over and it’s time to eat. You can do this with a crate or by using a baby gate to create separation. To ensure that your dog associates this separation with good things, give them a super special treat to enjoy while you’re having dinner. Snuffle mats and slow feeders are great because they take time, are fun, and will provide your dog with lots of mental stimulation.