Jackson Galaxy lost weight through mental discipline, a commitment to make changes to his lifestyle (a proper diet), a gastric bypass operation and a loving wife who turned him to veganism and exercise. That’s my reading of the situation.

Discussion
I am an admirer of Jackson Galaxy because he understands domestic cats and he is a good presenter. He promotes cat welfare. He is successful and a celebrity. He learnt his trade the hard way by working in a cat shelter, studying cat behaviour and doing his utmost to improve the chances of adoption of the cats in his charge. No doubt he learnt how to give them confidence to make them more attractive to potential adopters.
Not everyone knows that at one time he reportedly weighed 400 pounds. I’m told that he had an addiction to food. He had a compulsion to eat junk food and became morbidly obese before 2007. For UK readers, 400 pounds is 29 stones approximately. Pretty huge in other words.
The way he looks now on his YouTube channel and on television tells us that he is about a normal weight with a good BMI. If a doctor looked at him they’d probably say he’s got a good BMI, which is a good sign that his internal organs aren’t covered in fat. When you see a fat person, you see the fat waistline predominantly but what you don’t see is the fat around the internal organs which causes them to malfunction which in turn causes illness.

Commitment
My research indicates that Jackson Galaxy lost weight through a combination of factors, the most important of which is a commitment to do it. I’ve not read this online but the starting point for weight loss must be attitude. It is a head game. It is about a change in attitude to your relationship with food and your lifestyle in general. And the change must be permanent. The concept of the diet is not selecting one of the well-publicised, commercialised “diets” which lasts five minutes causing weight loss and then weight gain when you give up.
Gastric bypass
“Diet” should mean a lifestyle change and that can only start inside a person’s head. I therefore commend Jackson Galaxy for committing to a permanent change in lifestyle. To help him on his way he had gastric-bypass surgery which as you might know shrinks the size of your stomach so you can’t physically ingest so much food. It must reduce appetite. Specifically, it is an operation in which the stomach is divided into a small upper pouch and a much larger lower remnant pouch. The objective is to make you eat less. That was a physical change which started with his mental change.

Wife
Another key factor is that he has a wife who is highly supportive. This is a huge benefit. Her name is Minoo Rihbar – a great name. She has a good face, the face of a good person. They were married in 2014 at a pet sanctuary in Utah with their dog Mooshka playing the role of the ring bearer, I am told. So he has a soulmate, lover and admirer to keep him on the straight and narrow and he has become a vegan.

Pleasure seeking, depression
An addiction to food is about seeking pleasure in eating. Often sugars in foods provide that pleasure. They tweek the brain and you can become addicted to them. I don’t know Jackson Galaxy’s mental state before he turned his weight problem around but I do know that overeating can originate in low self esteem, anxiety and depression. These are all the usual mental health conditions that a lot of people suffer from and understandably so and which cause other kinds of addiction. The world is difficult. It can be hard to cope. Seeking pleasure in food helps to cope but then you find that eating a lot of food makes it harder to cope because your health deteriorates due to obesity.
Apparently Jackson was addicted to junk food but that is what you would expect in an obese person. Although food addiction is related to the mental health issues referred to above you have to go one step back from that to find out what causes those mental health issues. They may be partly inherited, or perhaps there was trauma in a adult person’s childhood. There may have been abusive parenting or a myriad of other problems.
Discipline
When you ask how Jackson Galaxy lost weight, you have to answer by saying that the first step is the key, and that first step is driven by a change in attitude which in turn comes from a commitment to turn one’s life around. It’s a mental process and that takes an admirable amount of steel and discipline. Well done to Jackson Galaxy.