Nutrition
Protein and Skin Ageing: How Too Much and Too Little Can be Harmful
BY
Anjali Tiscia
Jun 23, 2025
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There is no denying the current protein craze. Scroll through social media and you’ll see influencers everywhere sipping protein shakes, buying protein packed snacks, piling on cottage cheese, and swearing a high-protein diet is the secret to toned abs, glowing skin, zero bloat, and basically perfect health. Unlike carbohydrates and fats, which have both had their fair share of bad press, protein seems to be everyone’s golden child. No downsides, right?
But here’s the thing: while protein is essential, more isn’t always better. In fact, going overboard (or not getting enough) can actually backfire on our skin and overall health.
At The Skin Insider, we are big believers in balance and love busting beauty myths with science. So, let’s unpack the protein obsession, dive into what it really does for our skin, and look at why both too little and too much can be problematic.
What is Protein and Why Does it Matter for Our Skin and Overall Health?
Protein is one of the three main macronutrients we get from food, right alongside carbohydrates and fats. It is made up of tiny “building blocks” called amino acids.
Once we eat it, our body breaks protein down into these amino acids and then reassembles them into all sorts of important body proteins like enzymes, hormones, immune cells, and structural proteins that repair and maintain our tissues (including skin).
It’s also no surprise protein has become such a hot topic lately. Beyond its role in repair and recovery, protein helps to keep us fuller and more satisfied after meals, especially when compared with refined carbohydrates. Its ability to help curb cravings is one big reason that it has gained such hype on social media and in wellness circles.
When it comes to skin, protein also plays a vital role. Those amino acids don’t just help build muscle, they are also behind the proteins that keep our skin youthful, resilient, and hydrated:
Collagen: Think of it as the skin’s scaffolding. Made mostly from the amino acids; glycine, proline, and hydroxyproline, it keeps skin firm and plump.
Elastin: The stretchy counterpart to collagen, built from amino acids like glycine, valine, and proline, which allow our skin to bounce back instead of sag.
Keratin: Rich in cysteine (a sulfur-containing amino acid), this protein strengthens the outer layer of skin while also giving hair and nails their toughness.
NMF (Natural Moisturising Factor): A cocktail of amino acids and small molecules formed when the skin protein, filaggrin, breaks down. NMF is what keeps our outer skin layers soft, supple, and hydrated.
Where Do We Get Protein?
Protein comes from both animal and plant-based sources, each with their own unique benefits.
Animal proteins (meat, poultry, fish, eggs, dairy) naturally contain all the essential amino acids in the right proportions and are generally more easily digested by the body.
Plant proteins (beans, lentils, soy, quinoa, nuts, seeds) vary in their amino acid profiles, but as long as we eat a variety of plant proteins, we will still get all the essentials. Also slightly less digestible than animal protein, but plants offer extra benefits like fibre and antioxidants that support gut health and skin resilience.
Beyond these whole foods, there are also isolated protein sources like protein powders (whey, soy, pea, rice, hemp, etc.) and collagen powders. They can be beneficial for certain people to complement whole foods.
What Happens When We Don't Get Enough Protein
True protein deficiencies are rare in the developed world, but certain conditions, like chronic illness, restrictive diets, or eating disorders, as well as the natural ageing process, can increase the risk of protein inadequacy.
When protein intake consistently falls short, it doesn’t just affect the skin. The whole body feels it: immunity weakens, muscles become frail, fatigue sets in, and signs like oedema, brittle hair and nails, and slow wound healing may appear.
Many protein-rich foods also contain essential vitamins and minerals like zinc, copper and vitamin A. Inadequate protein intake therefore can also mean inadequate micronutrient intake, which brings with it a host of negative effects on the body and skin.
For the skin specifically, inadequate protein means:
Collagen loss: Causing sagging, fine lines, and wrinkles.
Reduced elastin and keratin: Leading to dullness, fragility, and thinning hair and nails.
Compromised barrier function: Skin becomes dry, sensitive, and more prone to irritation.
Slower regeneration: Blemishes, cuts, or inflammation take longer to heal.
Oxidative stress: Amino acids from protein are also needed to create compounds like glutathione (a powerful antioxidant). If inadequate, our skin loses some of its defence against oxidative stress and accelerated ageing.
What Happens When We Get Too Much Protein
The effects of too little protein are fairly straightforward and expected I would say. But what might be a surprise to many is the downsides of too much protein, so let’s explore this in detail.
Excessive protein, especially from animal sources, can put a strain on the kidneys and liver, cause digestive discomfort and increase risk of cardiovascular disease (though this is often due to accompanying factors like saturated fats rather than protein itself).
When it comes to the skin, going overboard on protein can backfire by reducing hydration, accelerating ageing and driving inflammation. Here’s how:
Reduced Skin Hydration: Blood Urea Overload:
When we eat protein, our body breaks it down into amino acids, which are then used for building and repair. But there is a catch: the process also produces nitrogen as a byproduct. This nitrogen gets converted into urea and must be excreted by the kidneys through urine.
The more protein we eat, the harder our kidneys have to work to clear this waste. This increased workload means more water is pulled from the body to flush out urea. Over time, if fluid intake doesn’t keep up, this can leave the body in a slightly dehydrated state.
One study in athletes found that the more protein they ate, the more concentrated their body fluids became; a clear sign their bodies were running low on water. Interestingly, many didn’t even feel thirsty, a phenomenon sometimes called “silent dehydration”. And the high protein intake in this study (about 30% of daily calories) is similar to, or even less than, what many high-protein diets promote today.
In the skin, this dehydration often shows up as dryness, dullness, and a loss of that plump, dewy look we all want. In other words, a high-protein diet can quietly increase our water needs, making proper hydration even more important to keep skin glowing.
Accelerated Skin Ageing: AGE Formation and TMAO Formation:
When certain foods; especially those that are high-protein and high-fat (like red or processed meats) are exposed to high temperatures (think barbecuing, deep frying, or grilling), they produce nasty, toxic compounds called AGEs (short for Advanced Glycation End Products). And yes, the name is fitting… because AGEs literally make us age.
They mess with the structure of our skin’s collagen and elastin, leaving them stiff and less springy, while also driving inflammation and oxidative stress. The result? Skin (and whole body) that ages much more rapidly.
Another one to know about is TMAO (Trimethylamine-N-oxide, but let’s just stick with TMAO). It is a compound our gut bacteria make when we eat certain animal-based foods like red meat, eggs, and some fish.
In small amounts, it’s nothing to worry about, but high levels have been linked to inflammation throughout the body. And where there’s inflammation, there’s faster collagen breakdown and, of course, faster skin ageing.
Inflammation: Gut Microbiome Imbalances:
Our gut microbiome plays a huge role in our overall health, and diet is one of the biggest factors that shapes it. The good bugs in our gut love fibre and plant-based compounds, while the not-so-good ones tend to flourish when our diet is heavy in animal proteins and refined carbs.
When the balance tips in the wrong direction, it can trigger more inflammation in the body and raise the risk of chronic disease. And, as we explored in our blog on the gut-skin connection, those shifts don’t just stay in the gut. They often show up on the skin as acne, irritation, and accelerated skin ageing.
How Much Protein Should We Be Having?
The million-dollar question: how much protein do we actually need? The truth is, there isn’t a one-size-fits-all number since it depends on factors like age, gender, activity levels, and body composition goals. That said, there are some solid guidelines we use with our clients in clinic.
The Australian guidelines suggest around 0.8g of protein per kilo of body weight (or at least 10% of daily calories). But honestly, that is pretty minimal and usually not what we recommend. A more realistic sweet spot is about 0.8-1g of protein per pound of ideal body weight (IBW), or roughly 1.5-2g per kilo of IBW. (You can work out your ideal body weight here). For more individualised targets though, consult a dietitian.
But, as you have probably gathered, it is not just about hitting a number. Where your protein comes from, and what you’re pairing it with, makes all the difference, and that’s what we’ll dive into next.
How Can We Reduce the Negative Effects of a High-Protein Diet?
By now we hope it’s clear that protein is absolutely essential for our health and wellbeing. But it should also be clear that chasing the high-protein craze without context can come with downsides.
The real takeaway? If you choose to boost your protein intake, do it with awareness and with the know-how to keep it safe, balanced, and truly supportive for your skin and overall health. So to finish up, let’s explore how to reduce the downsides of a high protein diet:
Include Animal and Plant Proteins:
Most of the downsides of protein show up when our intake leans too heavily on animal sources like red meat, poultry, eggs, dairy and fish.
These foods can absolutely have a place in a healthy diet, but it’s worth balancing them with plant proteins such as legumes (lentils, beans, chickpeas), tofu, nuts and seeds. Not only do plants still provide the essential amino acids we need, they also come packaged with fibre, antioxidants and phytonutrients that help protect our cells from ageing.
In fact, one study found that simply swapping a single serving of red meat for a plant protein, like legumes, was linked to a 62% lower risk of kidney disease progression. It is important to note that this study was conducted in a population with kidney disease, but does still highlight the benefits of incorporating plant proteins also.
Prioritise Dietary Fibre:
Speaking of fibre, if you decide to increase your protein intake, please do not neglect fibre. Fibre is phenomenal when it comes to gut health, chronic disease prevention and even weight management.
Incorporating plant proteins can help with this but also include other fibre sources wherever you can. This includes all fruits, vegetables, nuts, seeds, legumes and wholegrains. Research shows that hitting your fibre goals can even offset some of the gut-related downsides of a high-protein diet.
In Australia, the recommendation is 25-30g of fibre per day from food, however in the clinic we often recommend more than this for many clients.
Keep Hydrated:
High protein consumption can be dehydrating and this can have negative effects on our skin health and appearance. If you’re upping your protein, make sure you’re also upping your fluids.
We dive deep into hydration and skin in another blog that you can read here, but as a rule of thumb, aim for around 30-40mL of water per kilo of body weight, in addition to other fluids and plenty of hydrating foods.
