There’s a newish book out called BURN, all about the science of metabolism. As a personal trainer and nutrition coach I had to read it. (This is not an advertisement, I swear.) What blew my mind is that the author found that we actually do not burn more calories at the end of the day from exercise. Crazy, right?
How it works is, your body will suppress energy output (calories burned) from its other systems when you work out, so that at the end of the day you will still burn roughly the same amount of calories from day to day.
The good news is that you can finally ditch that cardio! Heh heh. The bad news is that the only way to lose weight is to eat less than you burn. Period. But this is actually good news too. Because it's ridiculously simple. Not easy, but not complicated either.
Here's what you can do—
Find out your BMR. find a BMR calculator online and plug in your info. You will burn more calories per day since you do move, and there are caloric needs calculators too… but there is a ceiling. Your body just won’t burn more than a certain number of calories a day. So if you think this is all bullshit, and you choose to exercise like a crazy person 24/7, then your body will not have the resources to operate its other systems. You will get sick. Or injured. Or depressed. You might lose your reproductive health, etc.
For me, I burn about 1200 calories a day doing nothing, and no more than 2000-ish a day moving around at my "moderately active" pace. (I always choose moderately active from those drop-down menus.) To lose weight realistically, I subtract only a few hundred calories and so I aim to eat 1700 calories a day, prioritizing protein and unprocessed food. I also strength train in order to create more lean mass. And because I love it.
Quick exercise note: working out might not help you lose fat but according to the author, it will help you know when you've eaten enough. It will help regulate your appetite and satiety cues. If you've ever wondered why you tend to eat better, or less on the days you exercise, it's this. Laying around all day can actually find you eating more, not because you're bored out of your mind, but because your satiety cues are not working properly. Of course there are a whole bunch of other reasons exercise is good for you but that's a post for another day.
Oh, one more thing. Notice that I said I prioritize protein and unprocessed foods. This is not just because protein helps me build muscle mass as a strength athlete, or because unprocessed foods are healthier, but because in terms of fat loss, both are satiating. Processed foods like fast food and boxed snacks are designed to be overeaten and to bypass our satiety cues. Let's face facts—cutting calories is hard. Humans evolved to store fat for those times when food is scarce. Our big smart brains depend on lots of calories, and hunger is not something easily conquered with "mindset" and "willpower." We need all the help we can get.
Okay, back to calories (or kilocalories as the author points out is the correct term). It took me years of experimenting to learn that 1700 is my magic number. It's a comfortable number. Any fewer calories and I inevitably binge, or quit, or both. Any more calories, and the scale won't budge.
If you're still thinking this is bullshit, because Michael Phelps, then you just have to read the book. Pontzer dives into that whole complicated stew and makes sense of it.
At the end of the day, there is no one diet that magically works. Veganism, paleo, intermittent fasting, cabbage soup, grapefruit and cleanses can all take a hike. The ONLY thing that works is steady, consistent, and TOLERABLE caloric restriction.
Experience has taught me that when you start out, be conservative. Because after a few months, you might plateau and will need to cut more calories. So make sure you leave room to cut more when the time comes. For now, choose a realistic, SANE amount of calories based on your needs, and go for it. You're looking to drop about a pound a week. Be consistent. Be kind to yourself. And be patient.
Hope this helps!