I also do 20 minutes of moderate exercise & get 5k steps in everyday
You CAN, but all the long-term studies doing just that say you probably WON’T – at least not by itself. The good news is that since you’re on the IF subreddit, your already planning to tip the odds in your favor!
The “eat X cal less per day to lose 3500/7X lbs per week” been the standard advice for years, but it naively assumes your metabolic calorie expenditure remains constant. It doesn’t. Energy metabolism is highly regulated, our bodies aren’t stupid, and it will tend to respond to deficits by reducing expenditure because it cannot access fat stores until your insulin level drops and you use up your glycogen stores. Your body can drop your BMR up to 50% by doing things like lowering your HD, BP, body temp, reducing fidgeting, reducing other cell processes like repair.
However, if you combine a caloric deficit with fasting, then your odds of succeeding go WAY up because more of your time will be spent with the “door to the larder (fat) open” hence, your body won’t be calorie limited and won’t be as inclined to drop your metabolic rate (since it’s got hundred of thousands of fat calories available). That’s also the thinking behind keto and low carb diets, since you aren’t restocking the glycogen stores fully, so you remain in ketosis (fat burning) most if not all of the time.
Now, I’m skirting the whole BMR vs TDEE thing, because I find TDEE often overestimated our calorie needs, so I think you are wise to focus on BMR – just remember that your body has plenty of tricks to go lower than your computed BMR. If you find yourself losing weight faster or slower than you want, you can adjust the amounts, types, and timing of your eating.
Good luck!
I’m only 2 weeks in, doing the 18:6, and have lost 6.2 lbs. About 3 lbs each week using a 500 calorie deficit. I track using the Fitbit app, which calculates my required calories each day, depending on my activity for that day. Some days I need 1500 calories, some days 1900… Just depends. It’s important to try to stick to the required amount each day, because not eating enough can be just as bad as eating too much.
I know that should only result in a 1 lb loss/week, but I’m also tracking fat %, and 5+ lbs of the 6 are fat. I’m loosely paying attention to my macros in the Fitbit app and am trying to get enough protein. Also drinking only water and tea, at least 64 oz each day, and cut out most dairy. Not saying this will work for everyone, but it’s what’s working for me. Nothing I’ve tried in the last 7 years has worked, including trying a personal trainer and dietician for a year. I have PCOS so it’s a little harder.
For context, I’m a 5’8” female, starting weight 184.2, CW 178. Goal weight 150.