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When determining protein intake, do I use my weight now or my goal weight?


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Hi all! First of all, I am a strict ethical vegan, so please might I ask you to take that into consideration in any dietary advice you might elect to offer me in response to this post. Just to be clear, that means I will not, for ethical reasons, consume any animal products, no products manufactured or harvested with slave labor or other forms of manifest exploitation, and no products that are known to cause widescale ecological devastation (date palm oil, avocados, etc.). It makes things a tad challenging, but I find that part of feeling good means not knowingly doing evil stuff with respect to my caloric intake. I make no judgments about what other folks choose to consume. Thanks awfully for your consideration! <3

First time poster but have been doing CR for about 3 months now and am happy to say I've lost 35 pounds. I have a bunch more to lose to get down to a <21 BMI, but I'm making good progress at around 2 pounds per week (which is, as of this writing, the upward limit of what is a safe, sustainable pace based on my best understanding from reading several CR books both old and new). I'm currently working through Dr. Fontana's book "Path to Longevity" and he brings up the issue of protein consumption. He has several different bits of data about it: first he says that the FDA recommends 0.6g/kg of body weight or more to avoid deficiency. Then he says 0.83g/kg of body weight is what is optimal and sufficient for most people based on a European study and he indicates that this is what centenarian Okinawans typically eat. He then says later on that an optimal ratio of 1:10 for protein to carbs is best for longevity in a variety of mammals and suggested that Okinawans were eating about 9% of their calories from protein.

So all of this leads me to do maths to see where I'm at. I'm using the CRONometer app and I"m using the macronutrient ratios of 24.5% protein to 43.5% net carb to 32% fat. I modified that slightly off of a post my partner showed me from CR Society, I think from one of Dean's dissertations/treatise which indicated that the aggregate mean ratios were something around that among CR Society folks polled. I tweaked the numbers slightly to get the total grams of protein required per day to display 1 gram per kilogram of my CURRENT weight. I am currently at 317.6 pounds which, at 38 years old and 6'4", is much too much for longevity and risk of disease and what have you, so I'm continuing to lose steadily. My goal weight is about 156-160 pounds which lands me at around 19-19.5 BMI or so.

So what I'm wondering is: should I be looking to eat 0.83grams of protein per kilogram of my GOAL weight of 160pounds which is about 72.5kg and therefore  about 60.2g of protein per day (which is handy because it's about 30g per meal since I only eat two meals a day and that's about the upper limit of what the human metabolism can usefully extract from a single meal, at least according to the references that Dr. Fontana cites). OR, should I instead be eating 0.83 grams per kilogram of my current weight of 317.6 pounds which is about 119.5g of protein?

I know too much protein leads to oxidative stress, inflammation, and susceptibility to a host of diseases. I know too little leads to muscle wasting and metabolic insufficiencies. At around 120g of protein and only eating 2 meals a day, I would have to get about 60g per meal or have 30g per meal and two snacks where somehow I get an additional 30g per snack and do not get much else in the way of calories (not easy to do), and the difficulty of doing that strikes me as a likely indicator that it's too much protein. However, I do not want to make assumptions about this and go to lower protein and find that I become ill.

I should note that in order to lose 2 pounds per week, I am eating at a 998 kcal deficit per day (some days a bit more if I just don't feel hungry and have less than or equal to about 150kcal left for the day). Typically I'll go a few days where I only lose 0.2 pounds or so, then have a day where I suddenly drop 1.5-2 pounds. I have at no point felt ill or weak or faint other than the first 2 or 3 days of CR where I think I was adjusting to the lower calorie intake. I think the removal of nearly 1k kcal from my diet makes the protein percentage be much higher (~25%) of my diet than if I were eating maintenance-levels of protein, in which case it would be closer to the 10%-ish level Fontana describes.

Anyway, that's my question and the context in which it's being asked. Thank you for any insight you can share!

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Welcome DeadStar!

It sounds like you are taking a very sensible approach to your diet given your current situation. Congrats. And kudos on your diet choice from another ethical vegan.

Regarding protein, here [1] is a good review of the literature on protein needs during weight loss. You are right to be concerned about getting adequate protein to preserve muscle mass during weight loss. But I wouldn't stress out too much about getting the exact right amount. If I were you I'd target 90-100g per day and focus more on making sure to get enough exercise, particularly resistance training, to maintain muscle mass while you drop your weight. Walking would also be highly beneficial for cardiovascular health.

Good luck!



1. Adv Nutr. 2017 May 15;8(3):511-519. doi: 10.3945/an.116.014506. Print 2017 May.

Preserving Healthy Muscle during Weight Loss.

Cava E(1), Yeat NC(1), Mittendorfer B(2).

Author information:
(1)Center for Human Nutrition, Washington University School of Medicine, St. 
Louis, MO.
(2)Center for Human Nutrition, Washington University School of Medicine, St. 
Louis, MO mittendb@wustl.edu.

Weight loss is the cornerstone of therapy for people with obesity because it can 
ameliorate or completely resolve the metabolic risk factors for diabetes, 
coronary artery disease, and obesity-associated cancers. The potential health 
benefits of diet-induced weight loss are thought to be compromised by the 
weight-loss-associated loss of lean body mass, which could increase the risk of 
sarcopenia (low muscle mass and impaired muscle function). The objective of this 
review is to provide an overview of what is known about weight-loss-induced 
muscle loss and its implications for overall physical function (e.g., ability to 
lift items, walk, and climb stairs). The currently available data in the 
literature show the following: 1) compared with persons with normal weight, 
those with obesity have more muscle mass but poor muscle quality; 2) 
diet-induced weight loss reduces muscle mass without adversely affecting muscle 
strength; 3) weight loss improves global physical function, most likely because 
of reduced fat mass; 4) high protein intake helps preserve lean body and muscle 
mass during weight loss but does not improve muscle strength and could have 
adverse effects on metabolic function; 5) both endurance- and resistance-type 
exercise help preserve muscle mass during weight loss, and resistance-type 
exercise also improves muscle strength. We therefore conclude that weight-loss 
therapy, including a hypocaloric diet with adequate (but not excessive) protein 
intake and increased physical activity (particularly resistance-type exercise), 
should be promoted to maintain muscle mass and improve muscle strength and 
physical function in persons with obesity.

© 2017 American Society for Nutrition.

DOI: 10.3945/an.116.014506
PMCID: PMC5421125
PMID: 28507015 [Indexed for MEDLINE]

Conflict of interest statement: 3: Author disclosures: E Cava, NC Yeat, and B 
Mittendorfer, no conflicts of interest.

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the seminal study by Rand et al., a metanalysis upon which the officially accepted protein requirements are based (ex. suggestions from Fontana, Longo, and many others), does not specify the BMI of subjects involved. It does specify that protein requirements is dependent on energy input though and that the data have not been corrected for this confounding factor. Actually, the data is a hodgepodge of many diets, individuals, both sexes, ages, energy inputs and so on.

The result is a very variable distribution of data. Which by the way are expressed in Nitrogen per kg per day, so a conversion is needed which is one more variable of itself (another source of uncertainty).

To make a very long story short, the official quantity of 0.83 gr kg-1 d-1 is a very cautious estimate, the 97.5 percentile of the requirements and by itself should suffice to meet the requirements of 97.5 people out of 100.

The method has been recently criticized, but still remains the official reference for many agencies like the WHO. It includes all kinds of protein but it is specified that it should be referred to 'high quality protein', the kind you don't eat (meat, fish, eggs, milk').

On the other side, in the same article is reported that soy protein is of high quality. And the data do include some  plant-based diets.

Bottom line, what I would do in your place.

You being a vegan, I would increase the RDA by 10 or 20%, and I would base it on a more average BMI, like 23= 190 pounds = 85.5 kg.

This would result in 78 to 85 grams kg-1 d-1 of protein, close to Dean's estimates, which would include the presence of energy expenditure such as exercise.

If you don't go below such a threshold, statistically you are guaranteed of meeting your daily requirement.


Edited by mccoy
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To make things even more to the point, the article posted by Dean specifically deals with protein requirements in a state of energy deficit. The suggestions if it is desired to preserve muscle mass are pretty clear, at least theoretically.




Strategies to prevent the weight-loss–induced loss of muscle mass

Regular physical activity, especially resistance-type exercise training, and high protein intake (1.25–1.5 times the RDA for sedentary persons and >1.5 times the RDA for those who exercise) are recommended for persons with obesity who undergo weight-loss therapy to limit the loss of muscle mass (8082), because dietary amino acids, insulin, and contractile activity are the major regulators of muscle protein synthesis and breakdown (83). Amino acids and dietary protein stimulate muscle protein synthesis in a dose-dependent manner ≤ ∼20 g protein/meal (84, 85). Insulin is a potent inhibitor of muscle protein breakdown and maximally suppresses muscle protein breakdown at plasma insulin concentrations of 15–30 μU/mL (8689). Exercise (both resistance and endurance type) improves insulin sensitivity (90, 91) and stimulates muscle protein synthesis (92). The effects of increased physical activity, exercise training, and increased protein intake during weight-loss therapy on muscle mass and muscle function are summarized in the following sections.


In your case, always taking as a reference a bodyweight of 85.5 kg, if exercising you would need more than 106 grams of calories per day, according to the article.

On the other way, I would realistically expect some muscle mass loss, bodybuilders always lose muscle mass before when in energy deficit before contests, even if they are on steroids, insulin, hi-proteic diet and so on.

At the end, you may settle into whatever amount you are comfortable with, in the range from 85 to 110 grams per day, depending on days. That's always more than the 60 grams per day you cite, but less than your present 120 grams per day. And, accepting the inevitability of the loss of some muscle mass (which you can always recoup later on) you may even settle on a more moderate amount of 85-90 grams per day. Making sure the aminoacids requirements in cronometer are respected (vegetable protein powders are good in this respect and used by most vegan bodybuilders).



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  • 2 weeks later...

Hey, I just wanted to follow up on this. So I had down-regulated the amount of protein I was consuming to comply with Dr. Fontana's "more than 30g of protein in a meal is oxidised and not metabolized as protein" (I'm paraphrasing) comment in Path to Longevity. I found that my weight plateaued and then I started gaining slightly. Now that may have been a fluctuation/fluke, but if so it persisted for about a week and a half whereas I had been losing very consistently (the slope of my weight loss line is almost a perfect straight line outside of that anomalous period). I went back up to higher protein intake so as to achieve 95-100g of protein as a minimum (based on my weight) and *immediately* started losing weight again the very next morning at dry weigh-in. I've now come down around 3 pounds since that point. I wanted to leave this note for posterity in case anyone was feeling as discouraged and hopeless as I was for a bit there! The weight *will* come off if you follow the dietary guidelines of CR: it's physically (i.e. as in "the laws of physics", thermodynamics and all that) impossible for it not to at caloric deficit + exercise + nutritional sufficiency. So stick with it, realize weight may fluctuate, try upping protein consumption a bit during the period of loss, and look forward in hope to a slimmer, more long-living you!


P.S. I'm down to 314.5 today. Goal weight is around 175-180. I've got a long row to hoe, but I'll get there. Big "I'm under 300 pounds" party at the end of the summer being celebrated by digging hugelkultur mounds and moving several tons of logs with hand tools for kicks and gardening. Hoowah!

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