A 150-pound woman weighs about 68 kilograms, and her protein needs land somewhere between roughly 54 grams and 150 grams per day depending on her goals, activity level, and life stage. The official U.S. Recommended Dietary Allowance sits at 0.8 grams per kilogram of body weight, which works out to about 54 grams daily. But a growing body of research suggests that number is too low for most women who are active, trying to lose fat, preserving muscle as they age, or pregnant. The real answer requires a bit more nuance than a single number.
Why the Standard Recommendation Is Probably Too Low
The RDA of 0.8 g/kg/day was established using nitrogen balance studies, which measure how much nitrogen (from protein) you take in versus how much you excrete. This method tells you the minimum amount of protein needed to avoid a net loss of body protein, but it does not tell you the amount needed for optimal health, muscle maintenance, or performance. Newer research using a technique called indicator amino acid oxidation has consistently produced higher estimates. A scoping review of 14 such studies found that protein requirements were higher than the current reference values for every sex, life stage, and activity level examined.1PubMed. Evaluation of protein requirements using the indicator amino acid oxidation method: a scoping review A separate study using the same method confirmed that breakpoint estimates exceeded those derived from older nitrogen balance work.2PubMed. Estimation of the protein requirements of young men and women using the indicator amino acid oxidation method
For a 150-pound woman living a mostly sedentary life with no particular fitness or body composition goals, eating around 54 grams of protein a day will keep her from becoming protein-deficient. But “not deficient” and “thriving” are different bars. Most experts in the protein research space now suggest that even relatively inactive adults would benefit from intakes closer to 1.0–1.2 g/kg, which translates to roughly 68–82 grams per day for our 150-pound woman. Once activity, aging, weight loss, or pregnancy enters the picture, the number climbs further.
If You Exercise Regularly
Physical activity increases protein needs regardless of whether you lift weights or run. One study comparing endurance-trained men and women found that the average protein requirement during recovery was about 1.6 g/kg/day for both sexes, with the recommended safe intake (the upper confidence interval) estimated at 1.81 g/kg for men and 1.89 g/kg for women.3PubMed. Protein Requirements Are Increased in Endurance-Trained Athletes but Similar between Females and Males during Postexercise Recovery That slight edge for women is worth noting: the assumption that women need less protein than men, gram for gram relative to body weight, does not hold up well in the data.
A review focused specifically on endurance athletes recommended a daily intake of about 1.8 g/kg, noting that the requirement can exceed 2.0 g/kg during periods of low-carbohydrate training or on rest days when the body leans more heavily on amino acids for fuel.4PubMed Central. Protein Nutrition for Endurance Athletes: A Metabolic Focus on Promoting Recovery and Training Adaptation For a 150-pound woman doing serious endurance work, that means roughly 122–136 grams per day or more.
For strength training aimed at building or maintaining muscle, a widely cited position paper concluded that to maximize muscle protein synthesis, total daily intake should fall between 1.6 and 2.2 g/kg.5PubMed Central. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution On a 150-pound frame, that range comes out to about 109–150 grams. If you are doing moderate recreational exercise a few times a week rather than training seriously, somewhere in the 1.2–1.6 g/kg range (roughly 82–109 grams) is a reasonable middle ground.
If You Are Trying to Lose Weight
Cutting calories makes higher protein intake more important, not less. When you eat in a calorie deficit, your body does not just burn fat; it also breaks down muscle tissue for energy. Eating more protein helps blunt that loss. A study of pre-obese and obese women found that those assigned to a higher-protein diet lost significantly less lean body mass during weight loss compared to women on a normal-protein diet, even though total weight lost was comparable.6PubMed. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women The higher-protein group lost about 1.5 kg of lean mass on average versus 2.8 kg in the normal-protein group.
Similar findings emerged in a study of postmenopausal women undergoing caloric restriction: those who consumed more protein retained significantly more lean mass and appendicular lean mass (the muscle in your arms and legs).7PubMed Central. Lean mass loss is associated with low protein intake during dietary-induced weight loss in postmenopausal women
Beyond muscle preservation, protein also makes dieting easier to sustain. Higher protein intake increases levels of appetite-suppressing gut hormones while decreasing the hunger hormone ghrelin, leading to greater feelings of fullness. Protein also has a higher thermic effect than carbohydrates or fat, meaning your body burns more calories digesting it.8Journal of Obesity & Metabolic Syndrome. Clinical Evidence and Mechanisms of High-Protein Diet-Induced Weight Loss For a 150-pound woman in a calorie deficit, aiming for at least 1.6 g/kg (about 109 grams per day) provides a solid balance of muscle protection and appetite control.
If You Are Over 50 or Postmenopausal
Aging creates a phenomenon researchers call “anabolic resistance,” where the body becomes less efficient at using dietary protein to build and repair muscle. The result is a slow, steady loss of lean mass, strength, and physical function over the decades. Several expert groups have suggested that older adults need at least 1.0–1.2 g/kg/day just to maintain muscle mass and function.9PubMed Central. Moderate Increase in Protein Intake Promotes a Small Additional Improvement in Functional Capacity, But Not in Muscle Strength and Lean Mass Quality, in Postmenopausal Women Following Resistance Exercise: A Randomized Clinical Trial For a 150-pound woman, that translates to 68–82 grams a day as a floor, not a ceiling. If she is also active and doing resistance exercise, she should think of that number as a starting point and push higher.
The issue is compounded by the fact that older women are among the most likely groups to fall short. National survey data have shown that roughly 7–9% of older adult women consumed protein below even the (arguably too low) Estimated Average Requirement.10The American Journal of Clinical Nutrition. Current protein intake in America: analysis of the National Health and Nutrition Examination Survey, 2003–2004 If you are in this age bracket and your daily intake hovers around 40–50 grams, you are likely losing muscle faster than you need to.
During Pregnancy and Breastfeeding
The current Dietary Reference Intake sets the Estimated Average Requirement for lactating women at 1.05 g/kg/day, but research using amino acid oxidation methods found that actual needs during breastfeeding are higher than that. The same research group estimated protein needs during late pregnancy at about 1.52 g/kg/day.11PubMed Central. Protein Requirements of Healthy Lactating Women Are Higher Than the Current Recommendations For a 150-pound pregnant woman in her third trimester, that works out to roughly 103 grams per day. During breastfeeding, the number likely stays elevated above the official recommendation, though exactly how far above remains under investigation.
These findings align with the broader theme across the research: official protein targets were set using methods that captured the minimum to prevent deficiency, not the amount that supports the increased demands of growing a fetus, producing breast milk, or recovering postpartum.
Your Menstrual Cycle May Shift Requirements Slightly
An underappreciated detail is that protein needs are not static across the menstrual cycle. A study measuring the requirement for lysine (an essential amino acid used as a proxy for overall protein need) found that amino acid oxidation was higher during the luteal phase (the roughly two weeks between ovulation and your period) compared to the follicular phase. The lysine requirement in the luteal phase was about 8% higher, and this increase was positively associated with levels of estradiol and progesterone.12PubMed. Phase of menstrual cycle affects lysine requirement in healthy women The practical takeaway is modest: you probably do not need to track your cycle and adjust protein by the gram, but if you notice increased hunger or cravings in the second half of your cycle, leaning into protein-rich foods rather than carb-heavy snacks may serve your body’s actual biochemistry.
Spreading It Across Meals Matters
How you distribute your protein throughout the day affects how well your body uses it. There is an old idea that the body can only absorb about 20–25 grams of protein per meal, and anything above that is wasted. That is an oversimplification. While muscle protein synthesis does appear to level off beyond 20–25 grams of high-quality protein in a single sitting, the excess amino acids are not simply discarded; they are used for other tissue-building processes.5PubMed Central. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution
That said, spreading protein across the day is still better for muscle outcomes than cramming it all into one meal. Research on older adults found that people who ate at least one or two meals containing 30 grams of protein or more had significantly greater leg lean mass and strength compared to those who never reached that threshold at any single meal. The association plateaued at about 45 grams per meal for those who hit the threshold twice daily.13PubMed. Per meal dose and frequency of protein consumption is associated with lean mass and muscle performance
For a 150-pound woman aiming for 100–120 grams per day, a practical approach is three meals of roughly 30–40 grams each, or four meals of 25–30 grams. If you currently eat a low-protein breakfast (say, toast and coffee), shifting that meal to include eggs, Greek yogurt, or a protein shake can make hitting your daily target much easier without any single meal feeling overwhelming.
Not All Protein Sources Are Equal
A gram of protein from chicken and a gram from lentils are not interchangeable in terms of what your body can do with them. Animal proteins tend to be more digestible and contain a more complete profile of essential amino acids, particularly leucine, which is the amino acid most responsible for triggering muscle protein synthesis.14PubMed Central. The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review Most animal proteins score above 90% on the Digestible Indispensable Amino Acid Score, while common plant proteins range from 45% to 75%, with soy and potato isolate approaching 80% when properly processed.15Investigación y Desarrollo. Proteína vegetal versus animal: análisis biológico comparativo de digestibilidad, perfil de aminoácidos y efectos metabólicos
This does not mean plant-based diets cannot meet protein needs. Isolated plant proteins, blends that combine complementary amino acid profiles, and modified plant proteins enriched with specific amino acids can match the digestibility and muscle-building effect of animal sources.16PubMed Central. The role of dietary plant and animal protein intakes on mitigating sarcopenia risk If you eat mostly or entirely plant-based, the key adjustments are to eat a somewhat higher total amount (to compensate for lower digestibility), combine different protein sources throughout the day (grains with legumes, for example), and include high-quality options like soy, pea protein isolate, or quinoa regularly.
Should You Calculate Based on Total Body Weight or Lean Mass?
All the numbers above use total body weight, which is the simplest approach but not always the most accurate one. Protein is primarily needed by lean tissue (muscle, organs, bone), not by body fat. For a woman who is 150 pounds and at a healthy body fat percentage, calculating based on total weight works well enough. But for someone carrying significantly more body fat at a higher total weight, using total body weight can overestimate needs, while using a “corrected” body weight formula can also introduce errors in either direction.17PubMed. Calculation of protein requirements; a comparison of calculations based on bodyweight and fat free mass
A study of masters athletes found that when protein intake was calculated per kilogram of lean body mass, there was no difference between men and women, both averaging about 1.4 g/kg of lean mass.18PubMed Central. Association between protein intake and lean body mass in a group of Masters Athletes If you know your approximate lean mass (from a DEXA scan or a reliable body composition estimate), you can use that as the denominator instead of total weight. For a 150-pound woman at roughly 28% body fat, lean mass would be about 108 pounds (49 kg), and targeting 1.4–1.6 g/kg of lean mass would yield 69–78 grams per day, which maps closely to the moderate activity recommendations based on total weight. For a 150-pound woman who is quite lean and muscular, the two methods converge even more closely.
Will Higher Protein Intake Hurt Your Kidneys or Bones?
The concern that high-protein diets damage kidneys is common, but the evidence is specific. High protein intake can increase the filtration rate in the kidneys, a phenomenon called hyperfiltration.19PubMed Central. The Effects of High-Protein Diets on Kidney Health and Longevity A meta-analysis confirmed that high-protein diets raised the glomerular filtration rate compared to normal or low-protein diets.20PLOS ONE. Comparison of High vs. Normal/Low Protein Diets on Renal Function in Subjects without Chronic Kidney Disease: A Systematic Review and Meta-Analysis In people with healthy kidneys, this increase appears to be an adaptive response rather than a sign of damage. However, for anyone with existing kidney disease, the extra workload is a genuine concern and protein intake should be managed with medical guidance.
Some older literature raised alarms about high protein intake and bone loss, based on the idea that metabolizing protein produces acid that the body neutralizes by pulling calcium from bones. More recent data paint a different picture. A large cross-sectional study found that higher total and animal protein intake were associated with higher bone mineral density in the total body and spine.21PubMed Central. Protein intake and bone mineral density: Cross‐sectional relationship and longitudinal effects in older adults Another study using national health survey data found a threshold effect in women: each additional gram of protein was associated with increased bone mineral density up to about 61 grams per day, after which the association plateaued.22Scientific Reports. Association between dietary protein intake and bone mineral density based on NHANES 2011–2018 In other words, getting enough protein supports bone health, but pushing intake extremely high does not appear to provide additional bone benefits.
Protein, Blood Sugar, and Gut Health
Protein influences blood sugar regulation through its effects on both insulin and glucagon. Eating protein alongside carbohydrates can moderate post-meal blood sugar spikes, which is one reason higher-protein meals tend to produce more stable energy levels throughout the day. For women with prediabetes or type 2 diabetes, this makes protein a useful dietary lever.23PubMed Central. Effects of protein intake on glucagon, insulin, and glucose dynamics: implications for diabetes
On the gut side, a less-discussed consideration is that high-protein diets shift the composition of gut bacteria and the metabolites they produce. An in vitro study found that increased protein availability boosted populations of proteolytic (protein-fermenting) bacteria and raised levels of metabolites like phenol, p-cresol, and ammonia. The responses also differed by sex: males saw greater increases in certain bacterial populations, while females produced more ammonia regardless of protein source.24PubMed Central. Do high-protein diets have the potential to reduce gut barrier function in a sex-dependent manner? This does not mean high-protein diets are harmful to the gut, but it does suggest that pairing higher protein intake with adequate fiber is a good practice. Most of the concerning metabolites from protein fermentation increase when undigested protein reaches the colon, and a fiber-rich diet helps keep things moving through before that happens.
Quick Reference by Goal
To pull this together into a practical snapshot for a 150-pound (68 kg) woman:
- Sedentary, no specific goals: 68–82 g/day (1.0–1.2 g/kg), likely adequate for general health, though the official RDA of 54 g is the recognized minimum.
- Moderate exercise: 82–109 g/day (1.2–1.6 g/kg), supporting recovery and gradual body composition improvement.
- Serious strength or endurance training: 109–150 g/day (1.6–2.2 g/kg), targeting muscle growth, performance, and optimal recovery.
- Active weight loss: at least 109 g/day (1.6 g/kg), prioritizing lean mass preservation and appetite control.
- Over 50 or postmenopausal: at least 68–82 g/day (1.0–1.2 g/kg) as a floor, more if exercising.
- Late pregnancy: roughly 103 g/day (1.52 g/kg), with needs remaining elevated during breastfeeding.
These are not rigid prescriptions. They are evidence-informed ranges that account for the fact that the old RDA was built to prevent deficiency, not to optimize muscle, metabolism, or performance. If you are currently eating 50–60 grams a day and want to move toward 100+, ramping up gradually over a few weeks and spreading intake across meals is the most sustainable strategy. Your kidneys will handle it fine as long as they are healthy, your bones will likely thank you for it, and you will probably find you feel fuller and recover better along the way.