>>21553739
Mackerel is a predator. There are far better, far cheaper fish varieties. My local fishmonger often sells a "fish of the week" for 5-8 euro/2kg (5 pounds-ish). Usually it's a white fish perfect for soup or stuffing, like gurnard or whiting.
>>21549338 (OP)
Follow the food pyramid. On one condition: only eat stuff you made yourself. Want a pizza, ketchup, mayo, soda, bread, mustard, sausage? Make it from scratch. No 2 wheat flours, sugars or tomato concentrates are the same. You got to know this stuff.
None of these diets last. Wether it's keto, vegetarian, Montignac, whatever. You have to change your way of life, your perspective. Only buy from people you can talk to. It's their job to tell you why something they sell is best for you. Don't grab shit from an aisle in whatever supermarket.
Get your shopping done on foot or with a bicycle. If you can't do that go hiking, jogging, cycling or swimming in the weekends/whenever you can. It's all about endurance sports, fitness is useless and demotivating. Spend your yearly holidays in the Rocky Mountains or the Dolomites. Get good shoes (look for vibram soles), 2 good jackets (one light, one heavy) and backpack to keep your food dry. There's NOTHING that'll make you lose more weight than a solid walk in the mountains. Plus we don't laugh at you here. We're not kids at the swimming pool. We're in the mountains, we look out for each other. There are plenty alternatives to proper mountains as well: Eifel and Black Forest in Germany. Ardennes in Belgium and France. Scotland is magnificent. I'm sure there's similar regions in the US and Canada.
Good luck.