T Nation

Optimum Deficit for Fat Loss?


*What amount of caloric deficit is optimum for max fat loss on obese and low muscle mass persons?

*How high of a deficit is too high for fat loss on a 'normal'/balanced macro nutrient diet?

*What happens to the body and fat loss on a 'normal'/balanced macro nutrient diet if the caloric deficit is too high (other than a large amount of muscle being spent on energy)?

*What happens to the body and fat loss if the caloric deficit is too high on a ketogenic diet?

*Is the ketogenic diet supreme to 'normal'/balanced macro nutrient diet at the same amount of caloric deficit for fat loss?

I think these questions should get me started. Please explain your answer in detail and the reason behind it.


Something to consider regarding optimal deficit:

"In conclusion, data from this study suggest that athletes who want to gain LBM and increase 1RM strength during a WL period combined with strength training should aim for a weekly BW loss of 0.7%."

source: http://www.ncbi.nlm.nih.gov/pubmed/21558571


BW(in lbs)0.007500 = total daily deficit.


I don't understand how you answer is relevant and that formula and study is for 'elite athletes' looking to shed fat while preserving as much as possible muscle and 1 rep max strength.

I'm not an elite athlete nor am I looking to preserve max absolute strength while cutting.


Depends on their height and how much LBM they have. In general, as little as possible that enables 1-3 lbs lost/week. I think the general calculation is LBM in lbs times 10-12 for a cut.

For an extremely obese person, losing more than 3-5 lbs/week (I'm talking for a 400+ lb person w/ 5 lbs) is probably pushing it. For most people, 1-2 lbs/week is enough to preserve muscle. If there is no muscle, I would still be hesitant to go much more aggressive, because you'd probably be better off losing fat and building strength (recomping) just because you can and the long term effects (keeping the fat off).

Fat loss plateaus and you are forced to cut cals or increase exercise. You will also likely continue to lose muscle. I would imagine there are some negative hormonal effects as well.

I wouldn't think keto or not matters. But I'm not sure.

no, different things work for different people. You may want to limit carbohydrate consumption, but going straight to keto seems needless, as you could just cut carbs over time and see if you end up there. That is, unless you don't really like carbs, in which case, it may be more sustainable.


This statement is at odds with the title of the thread you've started. It doesn't sound like you are after the optimum deficit at all.

Why not measure what you put into your body and aim for 1-2 pounds per week of weight loss? If you are over or under that, adjust.


calories in -calories out is an outdated paradigm.

'Optimum' fatloss is best achieved by training very hard, making super clean food choices and nailing peri workout nutrition/supps.