Protein After 40: How Much You Need to Keep Your Muscle as You Age

How much protein do you need after 40? At least 1.0–1.2 g per kg of body weight a day, or 1.4–2.0 g if you strength train, plus about 0.2 g/kg if all your protein comes from plants. Aim for about 0.4 g/kg per meal. And strength training matters even more than protein for keeping muscle as you age.

This guide explains what happens to muscle from 40, how much protein you need by body weight and per meal, how to make plant protein work, what changes for women, and what else helps.

What happens to your muscles after 40?

From around midlife, most people slowly lose muscle mass, and strength drops even faster. In a large study of adults in their seventies, strength declined about two to three times faster than muscle mass. So the quality of the muscle changes, not just the amount [1].

When this loss goes so far that it affects everyday life, it's called sarcopenia. The European definition now puts low muscle strength first, ahead of muscle size, because strength decides whether you can climb stairs, carry things and keep your balance [2]. This isn't about how you look. It's about function: stable joints, fewer falls and staying independent for longer. The good news is that muscle keeps responding to training well into old age.

Why do you need more protein as you get older?

Older muscle responds less to the same amount of protein. Researchers call this anabolic resistance. In one study, older men needed about 0.40 g of protein per kg of body weight in a meal to reach the maximum muscle-building response, compared with about 0.24 g/kg in younger men [3]. Put simply, a portion that works well at 25 may be too small at 60.

How much protein do you need after 40?

Here is what the guidelines say, and which group each recommendation is for:

• Minimum for older adults: the PROT-AGE expert group [5] and the European Society for Clinical Nutrition and Metabolism (ESPEN) [6] recommend at least 1.0–1.2 g of protein per kg of body weight a day for healthy people over 65. That's more than the general reference value for adults of 0.83 g/kg [4]. In your forties and fifties, it's a sensible minimum to work towards.
• If you strength train, at any age: the International Society of Sports Nutrition (ISSN) recommends 1.4–2.0 g/kg a day [7]. For women who train in perimenopause and after menopause, it advises the upper end of 1.4–2.2 g/kg [8].

Our rule of thumb for plant-based eating: if all your protein comes from plants, add about 0.2 g/kg to each recommendation. Plant proteins are digested slightly less completely and have a different amino acid make-up [12, 13]. A little more makes up for that. This isn't an official guideline, just a simple buffer.

Body weight	From 65, without training (1.0–1.2 g/kg)	plant-based (1.2–1.4 g/kg)	With strength training (1.4–2.0 g/kg)	plant-based (1.6–2.2 g/kg)	Per meal (approx. 0.4 g/kg)
55 kg	55–66 g	66–77 g	77–110 g	88–121 g	approx. 22 g
65 kg	65–78 g	78–91 g	91–130 g	104–143 g	approx. 26 g
75 kg	75–90 g	90–105 g	105–150 g	120–165 g	approx. 30 g
85 kg	85–102 g	102–119 g	119–170 g	136–187 g	approx. 34 g

Should you spread protein across your meals?

Yes. Older muscle needs about 0.4 g of protein per kg in one meal to respond fully, so two to three protein-rich meals work better than one big one. Many people eat little protein at breakfast and most of it at dinner.

The studies don't fully agree. One found a higher muscle-building response when protein was spread evenly over three meals [10]. Another found that the total amount mattered more than the pattern [11]. The practical answer: reach your daily total first, then aim for two to three meals with a decent portion of protein (see the table) rather than one big one. You don't need to time it to the minute after training (more on the "anabolic window").

A plant-based example day (approx. 110 g of protein, for about 65 kg with strength training):

• Breakfast: overnight oats with soy milk and a serving of protein powder (approx. 36 g)
• Lunch: lentils, quinoa and tofu in a bowl (approx. 30 g)
• Snack: high-protein soy yoghurt with pumpkin seeds (approx. 21 g)
• Dinner: tempeh stir-fry with rice and vegetables (approx. 26 g)

Does plant protein work as well after 40?

Yes, with two small adjustments. Plant proteins usually contain slightly fewer essential amino acids and are digested a little less completely than animal proteins. So the same gram amount can give a somewhat smaller response [12]. The fix is simple:

1. Eat a little more of it. That's what our +0.2 g/kg rule of thumb is for.
2. Combine sources. Soy, pea and rice complement each other.

A review on vegan diets for older adults comes to the same conclusion: muscle can be maintained, as long as you pay attention to the amount and variety of protein [13]. More in our guide Which vegan protein is best?

Is strength training more important than protein?

Yes. Strength training is the main signal for keeping muscle; protein provides the building material.

• In a meta-analysis of older adults, strength training added on average about 1.1 kg of lean mass in around five months [14].
• In a 12-week study of women after menopause, strength training clearly built muscle and strength, while a high-protein diet on its own did not [15] (read our summary).
• In a large analysis of protein supplements, protein improved the results of training, but less so in older participants than in younger ones [9].

The order of priority: strength training two to three times a week, enough protein every day, then everything else.

What changes for women over 40 and 50?

In perimenopause and after menopause, many women lose muscle and bone mass faster. Researchers are still working out exactly why. Studies link it both to falling oestrogen levels and to changes in everyday life, such as moving less. In a large Finnish study of women aged 47–55, the most active women had more muscle in every phase of the menopausal transition [16]. Hormones are only partly in your hands, but activity is, and that's where strength training makes the biggest difference.

What matters especially:

• Strength training, ideally with free weights: it's safe and effective after menopause [15].
• Protein at the upper end of the range: the ISSN recommends that women who train in perimenopause and after menopause aim for the upper end of 1.4–2.2 g/kg [8].
• Protein, calcium and vitamin D for your bones. Protein contributes to the maintenance of normal bones. Calcium is needed for the maintenance of normal bones. Vitamin D contributes to the maintenance of normal bones.
• More in our articles on menopause nutrition and creatine for women.

What else helps you keep muscle after 40?

• Vitamin D: contributes to the maintenance of normal muscle function. In winter, many people in Europe get too little from sunlight.
• Creatine from 55: daily creatine consumption can enhance the effect of resistance training on muscle strength in adults over the age of 55. The beneficial effect is obtained with a daily intake of 3 g of creatine, combined with resistance training at least three times a week for several weeks, at an intensity of at least 65–75 % of your one-repetition maximum, with the workload increasing over time. More on creatine
• Enough energy overall: if you eat too little in total, your body uses some of the protein for energy instead of muscle.
• Sleep and everyday movement: walking, taking the stairs and short "exercise snacks" all count.

Is a high-protein diet bad for your kidneys?

For healthy people, no. A meta-analysis found that higher protein intakes did not change kidney function in healthy adults compared with lower ones [17]. If you have a kidney condition, talk to your doctor before increasing your protein. More in Is protein harmful to the kidneys?

Checklist: protein after 40

• ☐ I eat at least 1.0–1.2 g of protein per kg a day (1.4–2.0 g with strength training).
• ☐ If I eat only plant-based, I add about 0.2 g/kg and combine sources.
• ☐ Two to three of my meals contain a decent portion (approx. 0.4 g/kg).
• ☐ Breakfast isn't my low-protein meal.
• ☐ I strength train two to three times a week.
• ☐ I keep an eye on vitamin D, especially in winter.

"I started strength training in my thirties, and what surprised me most wasn't how quickly I got stronger, but how much it changed the way I felt about getting older. Protein helps, but the real change comes from using your muscles." – Dr. Anna Falk, PhD chemist, sports nutritionist and founder of WAM

FAQ: Protein after 40

How much protein do I need after 40?

Most adults over 40 do well with at least 1.0–1.2 g of protein per kg of body weight a day. That is the minimum the PROT-AGE and ESPEN expert groups set for people over 65. If you strength train, the ISSN range of 1.4–2.0 g/kg applies at any age. For someone weighing 70 kg, that means about 70–84 g a day without training and 98–140 g with it.

How much protein do women over 50 need?

Women over 50 need at least 1.0–1.2 g of protein per kg a day. Women who strength train in perimenopause or after menopause should aim for the upper end of 1.4–2.2 g/kg, according to the ISSN. At 65 kg, that is about 91–130 g a day, or 104–143 g on a fully plant-based diet. Pair it with two to three strength sessions a week, because training is what tells muscle to grow.

Can I still build muscle after 40 or 50?

Yes, muscle responds to strength training at any age. In a meta-analysis of older adults, strength training added about 1.1 kg of lean mass in around five months. In a 12-week study, women after menopause gained muscle and strength with free weights. Progress can be slower than at 25, so regular training and enough protein matter more than ever.

Is plant protein enough as I get older?

Yes, plant protein can maintain muscle as you age, as long as you eat enough of it and vary your sources. Plant proteins are digested slightly less completely and contain fewer essential amino acids per gram. A buffer of about 0.2 g/kg a day makes up for that. Combining soy, lentils, beans, grains and seeds over the day covers all essential amino acids.

When should I eat protein?

Spread your protein over two to three meals with about 0.4 g per kg each, rather than eating most of it at dinner. For a 70 kg person, that is roughly 28 g per meal. Breakfast is often the meal with the least protein, so it is the easiest one to improve. The exact minute after training matters far less than your daily total.

Do I need protein powder?

No, food can cover your protein needs, especially if each meal includes a clear protein source such as tofu, tempeh, lentils or soy yoghurt. Protein powder is a practical option when appetite, time or a plant-based diet make your target harder to reach. A 30 g serving typically adds 20–25 g of protein to a breakfast or snack.

Plant-based protein with WAM

WAM Protein is a vegan protein powder made from soy, pea and rice protein. It's for people who want an easy way to add protein to breakfast or a snack without a very sweet taste: a 30 g serving provides 21–23 g of protein, depending on the flavour, sweetened with a small amount of stevia. Protein contributes to the growth and maintenance of muscle mass.

Sources

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[11] Kim IY et al. Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults. Am J Physiol Endocrinol Metab. 2015;308(1):E21-8. PubMed

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