Is a deficit of approx. 800-900kcal too much for one day?

[HeadfulofYouth]

In the run-up to Christmas and St. Stephen's dinners, I'm trying to keep my calorific intake as low as possible. Today, I will have a deficit from my BMR of around 800 to 900kcal. I estimate that I will have lost a pound by tomorrow morning.
However, I note that most users' deficits are in the 500-600 range. Is my deficit overkill? Will it excessively slow my metabolism? Should I eat a little more? I have no appetite as it is. Dinner is approaching (we eat it at 5-6pm in my family's house), and I have a large mug of cocoa at bedtime (I'm probably underestimating its calories - going off the tin, but I put quite a bit of powder in), so I'm safe from fainting.

[StrandedWhale]

The earliest evidence for lowered metabolic rate in response to fasting occurred after 60 hours (-8% in resting metabolic rate). Other studies show metabolic rate is not impacted until 72-96 hours have passed.

So to answer your question no ^^

[TommyArra]

You will not lose 1lb due to a 8-900 deficit. Around 3500 calories equates to 1lb of BF.

8-900 deficit is fine for the majority of a cut as long as "re-feed" days are factored in. These ensure you keep your metabolism up and also ensure various hormone levels don't drop excessively low.

I'm currently working with a 1000 Cal deficit on 5 out of 7 days per week. The other 2 days I eat to a maintenance calorific level, with an emphasis on complex carbs. This should, in theory result on a steady fat loss of 1-2lb per week and minimal risk of losing muscle.

[MrM27]

So you're safe from fainting? What are you doing to yourself? Starving yourself to that point is ridiculous.

You don't subtract from your BMR you subtract from your TDEE.

You are not going to get support here if you are Starving yourself.

[TommyArra]

^^ he's right...massively!

Although an 8-900kcal deficit from your actual daily kcals burnt is do-able.

[birdiefu]

OP is talking about an 800-900 deficit from *BMR*, which is completely outrageous for anyone, but especially at her stats. If you check her log, you will see her intake for one day is 475 cals, but according to her macro tracking of P:15g/F:11g/C:36g, actually at 303. This would be mostly coffee, a sip of juice, cigarettes, and eventually a sandwich.

OP, please considering your history in threads and journal, please take a step back and stop "dieting" as you are not doing your physical or mental/emotional state any good right now. Please mention this feeling of needing to extremely restrict to your therapist and get a referral to a dietitian also ASAP.

[blue9steel]

Today, I will have a deficit from my BMR of around 800 to 900kcal.

Whoa there Tex! Slow down. This is way too large a deficit since you're doing it from BMR rather than TDEE.

Anecdotal recommendation would be a max rate of 1% of bodyweight PER WEEK which for you would be a 550 calorie deficit from your TDEE per day.

Science recommendation varies with bodyfat, given your current 20% BF the max rate would be 691 calorie deficit from your TDEE per day.

You're exhibiting unhealthy behavior. You should eat more and consider seeking counseling.

[HereToFlex]

I agree with everyone's concern here.