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What's the largest calorie deficit possible before starvation mode?

Manuel Villacorta
Nutrition & Dietetics
It depends on how large you are and the amount of weight you have to lose. A larger person with more fat tends to have larger Total Energy Expenditure so they can have a 1000 - 1500 calorie deficit and still be okay. But, for someone who needs to lose 10 - 20 pounds of weight a large deficit could be detrimental to their weight loss as it could result in their metabolism shutting down. For these clients, I generally recommend a deficit no larger than 700 calories.

Based on my years of experience helping thousands of people sustainably lose weight I have come up with these general deficits for weight loss --
  • BMI greater than 30 (obese) = 1000 - 1500 calorie deficit
  • BMI of 25 - 29 (overweight) = 700 - 1000 calorie deficit
  • BMI less than 25 (those that want to lose 5 - 10 lbs.) = 500 - 700 calorie deficit
If you want to find out your customized total energy expenditure and your optimum deficit of calories for weight loss please visit www.EatingFree.com and use our free online tools.
Neal Spruce
Neal Spruce on behalf of dotFIT
Fitness
What you mean is what is the biggest deficit you can be in and not lose muscle/lean body mass (LBM). We say this because there is no starvation mode, only the myth and a bad excuse for not losing weight when supposedly dieting. First of all, any time you lose weight you lose both muscle and fat (1/4 muscle, 3/4 fat) unless you supplement and weight train. BUT even with weight training you can't lose any more than 0.7% of weight per week without losing muscle. For example, a person weighing 200 lbs can lose 1.4 lb/wk (750 calories per day deficit). BUT they must supplement at least a daily multivitamin and mineral (MVM). 

The greater the deficit the more you need to supplement, meaning ideally to preserve or increase LBM you need you need to consume a diet consisting of 500-1000 fewer calories than you burn, a MVM, and a pre/post workout formula. This is what all dieters should do because the goal is to increase LBM during weight loss to help burn more calories, not less. This can help offset the fitness/weight loss paradox: "The more fit and lighter we get, the fewer calories we burn when all things are equal and thus end up at plateaus, which forces us to make an unwanted adjustment.” If you want to lose weight very quickly, but safely, use our Sharecare Fitness Application located under the Coach tab; click here for access: http://www.sharecare.com/home/coach

Create your goal and you will receive the ideal plan to get you there.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.