Calories and weight loss

Under eating does not cause you to hold on to fat. Otherwise, people wouldn't die of anorexia. You lose weight if you eat at a calorie deficit. I think maybe your problem is overinflated calorie burn. I don't know very many people who can burn 1000 calories in 2.5 hours. What were you doing that burned that many calories, and are you sure you actually did burn that many? If you aren't losing weight, 99.9 percent of the time, it is because you are either eating more calories than you think, due to not measuring correctly, and/or over estimating calorie burn.

For calorie burns for running and walking, have a look at this calculator: https://exrx.net/Calculators/WalkRunMETs (Set Energy to NET)

If rucking is walking with a backpack, then use your weight plus the weight of your backpack in the Body Weight tab. Then lets see what kind of calorie count you get there. It's a pretty good check and not super overinflated like many apps, sports watches, and actually also the exercise database here has.

WillWalsh2124 wrote: »

Hello. My name is Will and I am an active 47yr old male that trains 5-6 days a week, including martial arts, lifting and rucking. The issue I am having the past 12 months is getting my weight down. I understand the calculations and of being in a caloric deficit. I understand macros, time restriction feeding etc...but to my question. If my calories are to low, i.e. 1000 + deficit, will my body hold onto the fat that I have? Today for example, I trained for 2.5hrs and burned ~1000 calories. I then rucked for 1hr burning ~900 calories. This means that my target calories of 2300 is now 4200!! I supplement with grass fed protein shakes and still can not get over 3700 calories in a day. Thoughts, recommendations?

Eating too few calories can have lots of nasty consequences...holding onto fat isn't one of them, but it can get pretty gnarly from a health standpoint. You are correct in your presumptions of how MFP works, but I'd also say your calorie burns are likely inflated. I've done my fair share of rucking and hiking and 900 calories in an hour sounds pretty overstated. The 1,000 calories in 2.5 hours may be more accurate depending on what exactly that was. In my cycling heyday 2.5 hours was usually my long training ride at tempo and I would burn that over the course of 35-40 miles or so...sometimes more depending on ride terrain. In other words, it was sustained tempo over a long period of time and miles.

And to Retro's point, strenuous activity like that is likely to be offset by decreased activity in your day to day. On long training ride days, I didn't do a whole lot afterwards except hang out (offsetting training calories with lower NEAT calories) where otherwise on a Saturday I might have been out and about most of the day doing stuff or doing yard work or whatever and just generally moving more throughout the day. It was pretty normal for me to take a good 2 hr nap or so in the afternoon after long training rides.

Ultimately this comes down to your own personal data. If you're dropping weight quickly, you're not eating enough. If you're not dropping weight, you're eating too much to do so. If you're gaining weight...well, you know the answer.

Lietchi wrote: »

WillWalsh2124 wrote: »

Yirara, that calculator has my 90min walk higher than my fitbit estimate, at 1163..

Watch out for net versus gross calories (including BMR or not including BMR). I don't know which burn fitbit shows, but be sure to compare like with like.

PS the calories you should be eating back are the net calories.