Calorie deficit

[Holbops]

Hi,

I've calculated a calorie deficit of 12,391 this week.  I read that a deficit of 3,500 generally equates to 1lb weight loss, therefore I should in theory have lost 3.5lbs. I've only lost 1.5lbs this week though. What's happening?

Thanks 

[wtksk8r]

Several things could be happening. If your deficit is 12391 for 7 days that means you are on an approximate 1700 calories/day deficit. That is a significant amount to be under in a day. Your body could be reacting to this by going into starvation mode which reduces the calorie it burns to stay alive. In addition, if you started exercising then you could be building muscle mass which is denser than fat and you could also just be replacing fat with muscle at this stage.

[Heybales]

Stress from attempting such a huge deficit.

Increased cortisol.

Increased water retained.

Not showing the fat loss expected (that 3500/lb is only for fat loss, not weight loss)

Do you have over 120 lbs to lose to healthy weight to make that deficit reasonable?

ETA: The starvation mode, aka Adaptive Thermogenesis, doesn't happen in 1 week, besides which first effect is body being slowed down - less steps being done, fidgeting, ect. Takes a few weeks for the worse effects of hair falling out, nails brittle, dry skin, and then longer before metabolism is slowed down.

But if that deficit is accurate - you will get there for sure!

Won't stop you from losing - but it sure means none of the numbers are correct you are using.

Sadly you can't gain muscle that fast.

If you are male in progressive strength training program not just starting out, eating adequate protein (which that deficit guarantees you are not), and eating in surplus (no to that one too) - you could gain 1-2 lb a month.

Much easier to lose a lb of muscle in a bad extreme diet than to gain a lb in bulking.

I'd be more concerned with this if not doing any resistance training.

The other potential is your logging is off.

You didn't burn as much as you think, you ate more than you think.

Did you log every bite you ate of everything by weight (except fluids)?

Because calories is per gram, not per cup, spoon, about 3 servings per package, ect.

What workouts did you do to cause the calorie burn?

If the Fitbit used HR-based calorie burn for the workouts (likely did), that formula is ONLY a decent estimate (not a measurement, calculated) for aerobic steady-state - not lifting, not intervals, not sprints, ect - all those are inflated calorie burn.

Also anything on the low end, like if walking bumped up into that range - that's inflated calorie burn.

Distance-based would be more accurate, like your daily activity uses - if the distance is accurate, since that is very accurate formula for calorie burn. More than HR-based calculations are.