What do you think is the quickest way to lose weight?

Chop off a limb.

There are no short cuts to losing weight. It is all about eating less calories than you burn. One pound of fat is ~3500 calories. Eat 500 less calories per day than you burn to lose ~1 lb a week.

Pick a deficit and way of eating you can live with that doesn't make you want to gnaw off your own arm or have you craving forbidden food. Make small changes and discipline yourself to stick with it. It's not a shortcut, but it'll help minimize binging and calorie blowouts that might set you back.

Drink more water, eat less junk food and move more.

Meth. NO, DON’T, JUST KIDDING. It’s fast, but sometimes speed kills.
Seriously, starvation diets may make you lose a lot right away, but you pay for it by slowing your metabolism (because your body thinks “uh oh, food is scarce, better try to minimize energy use and maximize fat storage to get us through the famine” because for millennia, famine was the only reason anyone didn’t eat, and only people whose bodies adapted this way survived long enough to pass on their genes.
(Btw, the reason meth works to get you really skinny when other starvation diets don’t, is that it ramps UP your metabolism at the same time it makes you not hungry, so you actually burn more calories just sitting there tweaking, and consume less. However, when you come down you may be (a) ravenously hungry with a tendency to wolf several candy bars and forget to brush, thereby eliminating any weight loss (or good teeth) you had, and (b) insane and in really bad health. Just like any other starvation diet, it’s not really sustainable).
Yeah, basically, 1-2 pounds/week is probably the best you can hope for over time, and it can be done with, as someone noted, a 500-calorie per day deficit; whether you create that deficit with added activity or less consumption or some mix thereof is up to you. If you are *very overweight* (think My 600-lb Life) and radically change your calorie intake and activity level to what is “normal” for much thinner people, your initial losses will be more dramatic, but that’s largely because moving a very heavy body actually uses a lot of calories, and many seriously overweight people have gotten to a point where they hardly move at all, so even minimal activity plus a *reasonable* (1500-2000 calorie/day) diet will yield much higher absolute numbers of pounds lost — 60 pounds in a month is not unusual in such cases. And when *anyone* first starts a diet, particularly if they add exercise to a previously very sedentary life, they may drop 3-5 lbs a week for the first few weeks, and be disappointed it doesn’t continue like that. But even that rate is probably not sustainable for more than a month for most people. And remember, as you lose weight, you will start to use fewer calories just to move your body through space in daily life because it takes less energy to propel 160 pounds a given distance than to propel 200 pounds the same distance. That’s why we slow down weight loss and hit plateaus — at that point we either need to reduce intake further or increase activity time or intensity, add wrist and ankle weights or other resistance, stuff like that.