The amount of time it takes to lose weight is controlled by both internal and external factors. Internal factors are those that you have direct influence over such as food choices and physical activity while external factors are a lot harder if not impossible to change.
Diet and Exercise
Diet and exercise are the two main tools at your disposal to adjust how quickly you lose weight. Losing weight requires that you eat less calories and burn more energy. By doing this, you create a calorie deficit which forces your body to burn fat stores and causes weight loss. If you create a bigger difference between the calories you eat and calories you burn, you'll lose weight faster.
How long is takes you to lose weight depends largely on how much you eat, how much you exercise and yes, your genetics. Since you can't control your genetics, don't waste your time worrying. Instead, focus on eating right and exercising enough. Some people can lose weight faster than others while eating more. If you're not one of those people, accept it instead of trying to change it.
Healthy Weight Loss
Healthy weight loss is around 1-2 pounds per week. The heavier you are, the quicker your weight loss will start out. This will eventually slow down and fall within the healthy weight loss range.
If you want to lose 1 pound per week, you need to create a calorie deficit of 500 calories per day. That means that each day, you need to burn 500 calories more than you eat. If you want to lose 2 pounds per week, you need to create a calorie deficit of 1,000 calories per day.
A calorie deficit can be created either through burning an extra 500/1000 (depending on your weekly weight loss goal) calories per day through more exercise, eating 500/1000 calories less per day or a combination of the two. For example, if you want to lose 1 pound per week, you can burn an extra 250 calories through exercise and eat 250 calories less which would give you a 500 calorie per day deficit.
To lose weight faster, you need to combine both proper diet and exercise. While it's technically possible to lose weight by dieting OR exercising, it isn't a realistic strategy. Try going on a treadmill and seeing how long it takes you to burn 1000 calories. This is also true of cutting 1000 calories out of your diet every single day. If you're used to eating 2000 calories per day, cutting down to a 1000 calorie intake will make your day very difficult.
Faster weight loss is more than just cutting calories and jumping on the treadmill. If you eat the right foods and do the most efficient exercises, you can build muscle, speed up your metabolism, promote satiety (helps you eat less) and prevent excess fat storage.
Any exercise can burn calories. Your goal should be to think about the long run, not the coming days, that's what a healthy lifestyle is all about. When trying to lose weight, most people go on a treadmill or stationary bike and burn as many calories as they can. Cardio has many positive health benefits but, devoting all of your exercise time to cardio while completely ignoring strength training isn't the best idea if you're looking to speed up your weight loss.
Strength training is used to build muscle; muscle is metabolically active meaning it burns calories 24 hours per day. The more muscle you build, the more calories you'll burn throughout the day, even when you're not exercising. Strength training also burns a good deal of calories, just like cardio. For the best health gains and fastest weight loss, you need to incorporate both cardio and strength training into your exercise routine.
Eating the right foods can also help you lose weight faster. Ditch snacks and meals that are high in sugar and made from white flour. These calories are digested quickly leaving you hungry soon after you finish eating. This will result in an increased intake of calories and because of the quick infusion of energy, your body will be more likely to store those extra calories as fat resulting in unwanted weight gain.
The Bottom Line
Though it might be tempting to try and lose weight even faster, don't. Weight loss that is achieved over the 1-2 pound per week range is usually not a permanent or healthy solution. The changes you need to make to lose weight faster are so drastic that you won't be able to keep them up for very long. Once you start your old habits up again, all that weight loss will be gone and you'll probably end up in an even worse spot than where you started.