Should be quite easy to lose weight at first, based on your ridiculous overweightness your diet must have been silly. Two simple rules:
1. Your stomach is the size of your fist. Choose portion size accordingly.
2. Eat 3 meals a day. Balance grains, fruit, meat, veg. Drink water where possible.
Your stomach is the size of a fist, but can expand to the size of a car........ ok not that much, but it can become very big. The problem is if you're massively active, say like that USA swimmer I've forgotten the name of, that wins everything, who eats 12k calories a day due to swimming all day every day.
You get used to eating at that level, your stomach gets used to X amount of food, and you get used to eating a certain type of food, and get used to eating that amount however often you ate.
Fundamentally many "fat" people have bad parents, who get them used to eating heavy bad carb diets, and its something VERY difficult to change because you can eat something else but your body is used to eating something else its become routine and normal.
The worst thing is those of us that get injured, because you're used to eating so much if you're very active and it takes a long time to eat less and your body still thinks its going to be doing the same things so constantly craves the normal amount of food. Often you also don't know an injury will be long term and it can get out of control before you know it.
I got injured at 16ish, got two bad knees but before hand was playing football almost every day after school, followed by hours riding my bike, just to get home as it got dark and eat for the 15th time that day. Wasn't eating well but was in a heavy growing(as in height) phase. THen out of nowhere both my knees went out, and in a couple months the eating without any exercise i'd gone up a stone or more, from then on everything sucked basically in terms of weight, knee's, fitness and eating.
One last thing, ignore skimmed/semi skimmed milk, unless you like it. Theres very little fat in full fat milk compared to skimmed milk, full fat milk is something like 4-6% fat anyway which frankly is nothing, and fat isn't bad, lactose on the other hand is the carbs in it, its a high GI carb, isn't very good for you and a lot of people are mildly intolerant of it(for me it makes me phlegmy and I don't get on well with it, love milk but avoid it as much as possible).
Milk is fairly high in carbs due to the carbs in it, not the fat, the fat is healthy, the carbs aren't. Full fat milk is a more complete drink, fat slows the absorbtion of food, including carbs, meaning removing fat from milk actually makes the carbs in it absorbed faster, meaning a higher peak in blood sugar levels and higher insulin spike to compensate.
The best thing you can generally do is well rounded meals with a good high quality fat content as you need the fats aswell as the other effects they have, fat fills you up and tells your body its not hungry for far longer than carbs do, they'll slow down sugar entering the body, and make a meal last longer before you get hungry.
If theres anything to remove from your foods, its carbs first, never fat or protein.
Thats the other problem, you get a weight problem and the government, and food stores have convinced half the country removing fat, and added carbs is healthy, its not, just incredibly cheap and easy for the people making the foods. Still to this day the advice to eat 50% + of your diet as carbs and reduce fat is the farmers of the US of A who grow and profit from growing grains and wheats, thats why they have this massive corn syrup industry, they put it in everything because they massively over produce carbs and have too much for people to eat, so they turn it into awful massively high GI sugar and put it into absolutely everything. IF theres any advice to trust, its not that of 50 +years ago from farmers who made the best profits on corn.
Ketosis is plenty healthy for regular and fairly long term weight loss, the only thing that makes it difficult for a maintenance plan is pretty simple, your hunger will reduce so far eating mostly fat/protein, that its hard not to lose weight , when you want to maintain your weight its very difficult to do so without any appetite at all, thats where carbs come in, easier to eat calories, more condensed calories, and a healthy level of carb intake, of healthy carbs, will tell your body to eat every several hours.
. Not sure if all bets are off if I become rich and famous 
