the first (and only) step is to eat at a calorie deficit. If the easiest way for you to do that is keto (which is typically because fats and proteins digest more slowly and make you feel full for longer) then great! but you can also lose weight eating nothing but fried donuts as long as you maintained that calorie deficit.

people love to think some gimmick is the reason they lost weight. nope. it may have made it easier for you to keep a deficit, so in that sense, sure, but the reality is that if you consume fewer calories than are burned you will lose weight, no matter what type of food you're eating. 100% guaranteed.

physics is pretty strict about thermodynamics.

You misunderstand. Aside from the fact that the "calories out" part of thermodynamics include carbon dioxide, sweat, shit, hair, skin flakes and anything else that you excrete (fiber has calories, but you can't use them, so they come out as shit, not stored as fat), what I'm saying is two things.

1. Calorie restrict all you want, but if you're eating high carb, you're likely not going to reduce your triglycerides without medication as they're made from carbs.
   
2. There's a human element too. For the same reason that abstinence only sex ed doesn't work, simply telling people to eat at a deficit doesn't work. If you feel hungry all the time, you will eventually cave. Insulin resistance (which is common and exacerbated by high carbs will leave you feeling hungry both at maintenance and even moreso at a deficit)
   
3. There's more of a human element. We grossly underestimate what we eat unless we're logging everything. It makes it easy to slip up and if the foods you're slipping up with perpetuate hunger (via insulin resistance which a lot of overweight people have developed), you're going through a hell you don't need to subject yourself too.

I've been following a low carb lifestyle for almost three years now. It's done wonders for my health and it has one key factor that no other diet ever had. I can stick to it without feeling like death.