MFP Predicted loss rates are optimistic

yarwell

MFP is based upon 500 calories a day equating to 1 pound per week of loss (3500 calories per lb - assumes some of the weight lost is not fat). More complex models have been published and validated against experimental data, and at least two are online as interactive calculators. I had a go at simulating the weight loss of a 200 lb 5'-4" 40 year old woman looking to get to 150 lbs in 180 days, a loss rate just under 2 lbs/week for which MFP would set a deficit of 1000 calories.

1. http://www.pbrc.edu/the-research/tools/weight-loss-predictor/ can be set to a maximum deficit of 1500 calories/day. At this setting after 6 months the predicted weight is 158.3 lbs, after 12 months 137.9 lbs. Calorie intake at this deficit is 1261 per day, as the initial TDEE is estimated at 2761 calories. Deficit 1500, average loss rate 1.62 lbs/week.

2. http://bwsimulator.niddk.nih.gov/ is more complex, I set this to the goal of 150 lbs in 180 days. The solution was to eat 1237 calories/day giving an initial deficit of 1423 calories/day from an initial TDEE of 2660 (RMR=1564), then to eat 2173 calories for "maintenance" - ending up at 152.6 lbs after a year. This achieved the goal at 6 months, then had a refeeding effect which put a bit back on. At day 180 the predicted weight range was 138.1 - 161.6 lbs using the default "uncertainty" setting of 10%. Deficit 1423, loss rate 1.94 lbs/week.

From this we can see that MFP's simple linear "500 cals/day per 1lb/week weight loss" approach is overestimating weight loss compared to more recent mathematical approaches, which give similar results to each other.

For fans of starvation mode, model 2 predicted a reduction of TDEE to 2400 by day 5 from its initial 2660.

For fans of Exercise More to Eat More I plugged in a 100% increase in physical activity to take the TDEE up by 725 calories a day, combined with a food intake reduction of 567 calories to 2092 per day (21.5% off original TDEE). Total deficit 1292 calories/day to achieve the same goal using model 2. After 1 year weight was 150.1 lbs eating 2159 calories - the two food intakes were very similar hence no refeeding bump when the extra exercise was dropped after 6 months.

omma_to_3

And estimators like that are the reason I'm having my BMR tested. I upped my net calories to roughly my BMR and I dropped from losing 4 to 5 lbs. a month to 2 to 2.5. I tried it for 3 months. The first site says I could lose 40 lbs. in a year by eating 1676 calories a day. The second says almost 1900 hundred. I'd gain at that level.

ladyraven68

I found for me that they underestimated.

I am 4ft 11, and MFP sets me at 1200 to lose 0.9lb per week.

When I initially switched to 1600 it said I would lose 0.1lb per week.

but MFP is not alone - I also tried this to see how I tracked, and lost more than it predicted too

http://www.myfitnesspal.com/topics/show/491087-my-gift-excel-spreadsheet-for-bmr-tdee-cut-build-and-ma

LadyL2012

Yeah, I've always wondered this. My 5 week prediction here at current rates is down 10lbs, but I've been on my plan 4 weeks and lost 6lbs, so that doesn't really add up....

julieh391

It has been right on for me. I put no thought into my BMR or TDEE. I just plugged in my stats, set my goal (2lbs/wk), and eat the calories it tells me (including exercise calories.)

soccermum75

Bump for later

gogojodee

Bump

terryrh

When i first started using the app i was loving the estimates but once i sat and thought about it (34lb's lost in 5 weeks) it was never going to happen.