How to gain weight healthily

Table top full of natural foods; avocado, eggs, mushrooms, strawberries, olives and olive oil, nuts.

Weight loss is a multi-million pound industry, and while having a learner stronger frame is best for our metabolism, a body that is underweight can be as much of a concern as one that is overweight.

This article is written to help inform about the best nutrition practices to follow to help gain weight in a safe and healthy way.

Sadly, because our society heralds low weight as the golden ticket to happiness and health, you may think there isn’t a problem with being underweight. The truth, however, is that being very underweight is not ‘healthy’ and can lead to a number of health problems.

The impacts of being underweight

Adequate and appropriate nutrition is crucial to healthy energy metabolism. The term metabolism is not related to weight loss. It’s the ability for our cells to create energy to drive all of our organs and systems to function properly. Without the optimal daily intake of vitamins, minerals, amino acids, phytonutrients and energy, optimal health and physical performance will not be achieved.


Even with what may be considered ‘adequate’ nutritional intake, energy demands may well exceed input and stores in the presence of emotional, social and physical stressors. These stressors deplete our nutrient reserves through a series of biochemical pathways, which if left unabated, will result in one or a number of systems being affected, in turn impacting our energy output and causing fatigue.

It could be the digestive system that has been impacted. For example, if you are not absorbing nutrients properly, the nutrients required in the pathway to make ATP—our ‘fuel’—are not as readily available. Or it could be that your adrenal and/or thyroid glands have been impacted and therefore energy levels are starting to decline as a result.

Iron-deficiency anaemia can also be a major cause of fatigue. Low iron levels can occur because the absorption process in the gut has become inefficient. Low levels of B12 and folic acid can also produce either megaloblastic or pernicious anaemia.

Fertility impacts

If you menstruate and become very underweight, you could find your period stops. This can lead to difficulties for those trying to conceive.

Weakened immune system

Being underweight can affect the immune system, meaning the body is less able to fight infections and you may find you pick up viruses and infections more easily.

Skin, hair, teeth or bone problems

If you are deficient in certain nutrients, you may notice your skin, hair and teeth are affected. You may notice problems with your teeth, dry skin, thinning hair and be at risk of Osteoporosis, a condition that causes bones to be more brittle and therefore prone to breaking.

If you are underweight, it is vital to initially consult your doctor for a full medical evaluation to check there are no medical causes. Once pathology has been ruled out and you have the all-clear from your doctor and want to gain weight to support your health and wellness, seeking support from a nutrition professional to help create a plan together to meet your goal weight can be an amazing support. 

How to gain weight for optimal wellbeing

Person eating a smoothie bowl topped with berries and coconut shavings.

The best way to gain weight healthily is to become informed on what different types of foods actually do for us. Information is power! Then, armed with this information, work towards a more balanced food plan. Two overarching principles apply:

Eat more frequently: When you’re underweight, you may feel full faster, and be tempted to eat large portions. I’d recommend eating five to six smaller meals during the day rather than two or three large meals.

Choose nutrient-rich foods: As part of an overall healthy food plan, choose whole-grain breads, pasta and cereals; fruits and vegetables; dairy products; non-processed protein sources; and nuts and seeds. Avoid CRAP (Colourless, Processed & Refined) foods.

So, with these overarching principles set, let’s get informed. Our food/fuel is made up of: 

The macronutrients
  • Protein
  • Carbohydrates
  • Fats
The micronutrients
  • Vitamins
  • Minerals
Polyphenols & prebiotics

The macronutrients are consumed in the largest amount and are needed for energy, muscle creation and maintenance. They provide the fuel that drives all our bodily systems—gastrointestinal, cardiovascular and immune systems—to operate efficiently. 

The micronutrients are consumed in miniscule amounts (milligrams and micrograms), but are vital for facilitating enzyme reactions in hormone and neurotransmitter synthesis. 

And then we have the bioactives: polyphenols and prebiotics, which have the ability to modulate gene expression, induce apoptosis (programmed cell death of defunct or worn-out cells), modulate intercellular signalling & enzyme activities and communicate with our immune system to induce ‘tolerance’.

With this in mind, let’s set out all their roles and then start piecing it all together.

The macronutrients

A tabletop display of natural foods; blueberries, ginger; almonds, oats, chia seeds, pomegranate, spinach and salad leaves.

In energy terms, 1 gram of carbohydrate or protein provides 4 calories, while 1 gram of fat provides us with 9 calories, making fats a far more efficient energy source.


Many demonize and become confused about carbohydrates, but keep in mind that it’s the amount of carbohydrate—high or low—is less important than the type of carbohydrate in your daily food plan. It’s more important to eat colourful, fibre-rich carbohydrates than to follow a strict diet limiting or counting the number of grams of carbohydrates consumed.

For example, whole grains that haven’t been tampered with, such as whole-wheat bread, rye, barley and quinoa are infinitely better choices than highly refined, processed and milled grain products such as white bread, crumpets, biscuits or chips.

What are carbohydrates?

Carbohydrates are made up of sugars, fibres and starches and termed either simple or complex.

The simple sugars are broken down very easily by the digestive system and enter the bloodstream for more or less immediate use.

Complex carbohydrates are either longer chains of sugar molecules (polysaccharides – many sugars) which take much longer to be dismantled, having a less dramatic effect on blood sugar.

And then there’s starch and cellulose, aka fibre. Cellulose is the main substance in the walls of plant cells and helps plants to remain stiff and upright. Unlike other carbohydrates, fibre isn’t broken down in the small intestine and heads to the large intestine. Thus it’s actions are many:

  • Increases satiety
  • Keeps blood sugar levels stable 
  • Feeds the gut microbiome, which plays an important role in weight management

Choosing carbohydrates

Carbohydrates provide the body with glucose, which is converted to energy used to support bodily functions and physical activity. But carbohydrate quality is important; some types of carbohydrate-rich foods are healthier than others:

The best sources of carbohydrates are the more complex category, such as unprocessed or minimally processed whole grains, vegetables, fruits and beans. They promote good health by delivering vitamins, minerals, fibre and a plethora of important phytonutrients.

Refined and highly processed or refined carbohydrates, which tend to fall in the simple sugar camp, include white bread, pastries, fizzy drinks, and packaged meals. These contain easily digested carbohydrates that may contribute to inflammatory weight gain (around the middle section of the abdomen), promote diabetes and heart disease and inhibit lean muscle gain.

Please don’t be afraid of carbohydrates, they are your friend. Just steer clear, for the most part, of the cereal, biscuit and ready meal aisle in the supermarket.

Try these tips for adding healthy carbohydrates to your diet to add lean muscle and drive achieving a healthy weight:

1. Always opt for whole grains

When buying bread, ensure the first ingredient is indeed a grain: wheat, rye, or some other whole grain—and even better, one that is made with only whole grains, such as 100 % wholewheat bread.

Opt for steel cut or old fashioned oats, rather than instant porridge that’s been over milled, or a cereal that lists a whole grain first on the ingredient list and is low in sugar.

A good rule of thumb: Choose a breakfast that has at least 5 grams of fibre and less than 6 grams of sugar per serving. A serving of Purition’s Macadamia & Vanilla, for example, has a fantastic 6.2 g of fibre and only 1g of sugar.

2. Think beyond the bread aisle

Instead of bread, try a whole grain in salad form such as brown rice or quinoa, which make for a great base in a poke bowl for lunch rather than a sandwich.

3. Choose whole fruit instead of juice

An orange has two times as much fibre and half as much sugar as a 350ml glass of orange juice. Or, rather than a piece of fruit, think about a fruity smoothie made with Purtion’s strawberry or banana flavour, which will provide excellent levels of protein, but is again low in sugar (2g) and high in fibre (6.3g).

4. Bring on the beans

Rather than fill up on potatoes (I’m not demonising the poor old potato, just encouraging a little more diversity), try beans for an excellent source of slowly digested carbohydrates. Beans and other legumes, such as chickpeas, lentils and hummus also provide a healthy dose of protein.


Protein is found throughout the body, in muscle, bone, skin, hair and nearly every tissue. It also forms the building blocks for our neurotransmitters like serotonin and dopamine, which we need to keep our mood buoyant and motivated. Protein also makes up the enzymes that power multiple chemical reactions that take place moment to moment in the body.

Protein is made from basic building blocks called amino acids, nine of which—histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine—are known as the essential amino acids, as they must come from our food.

How much protein do I need?

We’re all individuals, at different stages of our lives, with varying lifestyles. These variants mean we need different levels of protein at different stages of our lives. The most commonly cited standard is the Recommended Dietary Allowance (RDA): 0.8 grams of protein per kilogram of body weight per day. 

Adults need to eat more protein-rich foods when losing weight, dealing with a chronic or acute illness or facing a hospitalization. Any of these situations are deemed “stressful” to the body’s metabolism and as such process protein less efficiently and therefore need more of it to maintain muscle mass and strength, bone health and other essential physiological functions such as the immune system (antibodies are made from protein!).

An international group of Doctors and nutrition experts in 2013 recommended that healthy adults over the age of 50 should consume 1 to 1.2 grams of protein per kilogram of body weight daily—a 25 to 50 percent increase over the RDA. Its recommendations were subsequently embraced by the European Society for Clinical Nutrition and Metabolism.

While people may obsess over whether a protein is complete (i.e. contains all 9 essential amino acids at least in the minimum amounts), it’s much more important to ensure that between the proteins you’re consuming in a day, you have all bases covered.

Here is what 56 g of protein could look like for a woman that weighs 56 Kilos:

  • 150g broccoli: 4g of protein
  • 1 cup kale: 2g protein
  • 1 cup cooked wholegrain rice: 5g protein
  • 85g organic tofu: 24g protein
  • 1 cup plain yoghurt: 8.5g protein
  • 1 serving of Purition’s Macadamia & Vanilla: 15g

= 58.5g total protein

Choosing healthy protein

When we eat foods for protein, we also eat everything that comes alongside it: the different fats, fibre, salt, vitamins and minerals. It’s this protein “package” that’s likely to make a difference to health.

Try these tips for adding healthy protein packages to your food plan to add lean muscle and drive achieving a healthy weight:

1. Incorporate plant protein

Get your protein from a variety of plants as well as meat when possible. Eating legumes (beans and peas), nuts and seeds (which all of Purition’s range is packed with) is great for both your health and the planet.

To get a broad spectrum of amino acids, here are some examples for each category:

  • Legumes: Lentils, beans (adzuki, black, fava, chickpeas, kidney, lima, mung, pinto etc.), peas (green, snow, snap, split, etc), edamame/soybeans (and products made from organic soy: tofu, tempeh, etc)
  • Nuts and seeds: almonds, walnuts, hazelnuts, pecans, pistachios, cashews, hemp seeds, pumpkin seeds, sunflower seeds, flaxseed, sesame seeds, chia seeds
  • Whole grains: spelt, rye wheat, quinoa this is particularly high in protein), rice, wild rice, millet, oats, buckwheat
  • Other: While many vegetables and fruits contain some level of protein, it’s generally in smaller amounts than the other plant-based foods. Some examples with higher protein quantities include broccoli, asparagus, brussels sprouts, and artichokes
2. Choose animal protein wisely

Considering the protein package is particularly important when it comes to animal-based foods. Generally, poultry (chicken, turkey, duck) and fish are best. Eggs are a powerhouse of protein–6g in one egg!

When it comes to dairy, unsweetened yoghurt is a great choice, as are some cheeses like feta, goats and mature cheddar. Interestingly, cows milk isn’t actually as high in protein as you may think.

Avoid processed meats if you can, as they contain nasty preservatives that can hamper your metabolism.  


Foods containing fat have a mix of specific types of fats, which can be sectioned in three forms: Saturated, Unsaturated and Trans-Fats.

Saturated fat

Saturated fat, over the last 20 years has been vilified for being the cause of raising cholesterol, which in of itself is demonised and widely viewed as the smoking gun of chronic disease. The so-called cholesterol/lipid hypothesis proposed by Dr Ancel Keys has now been thoroughly debunked scientifically, yet mainstream medicine and the food industry don’t seem to have caught up.

Quite simply, our liver makes the majority (75%) of cholesterol, and for good reason! It’s a key component of every cell membrane in the body, is the precursor for all your sex hormones and is the main energy powerhouse for your immune system. The remaining 25% does come from animal food sources, e.g. saturated fat and eggs. 

Common sources of saturated fat include red meat, whole milk and other whole-milk dairy foods, cheese and coconut oil. Aim for no more than about 10% of your daily intake to be from saturated fats.

Unsaturated fat

Unsaturated fats, which are liquid at room temperature, are considered the most beneficial fats. They can lower inflammation and, as they contain double the calories (9 per 1 gram of fat), make a good choice for healthy weight gain.

Unsaturated fats are predominantly found in foods from plants, such as vegetable oils, nuts, and seeds. There are two types of “good” unsaturated fats:

Monounsaturated fats

Monounsaturated fats have a single carbon-to-carbon double bond. The result is that it has two fewer hydrogen atoms than a saturated fat, keeping them liquid at room temperature.

Foods rich in monounsaturated fat include:

  • Olive oil
  • Avocados
  • Nuts such as almonds, hazelnuts and pecans
  • Seeds such as pumpkin and sesame seeds

Omega-3 fats are arguably the most important type of polyunsaturated fat. The body can’t make these, so they must come from food. An excellent way to get omega-3 fats is to eat oily fish 2-3 times a week. Good plant sources of omega-3 fats include flax seeds and walnuts. Purition’s coffee and walnut product contains 7.8g of polyunsaturated fats per serving.

Trans fats

Trans fats are man made, through a commercial process termed hydrogenation and, ideally, should be avoided. Hydrogenation describes the process of adding hydrogen atoms to cheap vegetable oil, in order to make it solid at room temperature e.g. margarine. The food manufacturers love to use it in biscuits, cakes, breads, ready meals etc. It’s one of the most unhealthy so-called foods you can legally eat—so don’t! It provides no health benefits whatsoever. 

Choosing healthy fats

Try these tips for adding healthy fats to your food plan to drive achieving a healthy weight.

Eat less:

  • Vegetable oils: Soy, canola, corn, sunflower, safflower, grapeseed and peanut oils
  • Foods containing such oils, including: Margarine and butter substitutes, powdered milk substitutes and coffee creamers, snack foods, shop-bought salad dressings, ready meals, processed fatty food like sausage rolls, biscuits and cakes (although the odd bit of birthday cake, of course, is fine!)

Eat more:

  • Free-range, preferably organic, grass-fed and game meats
  • Eggs
  • Non-farm bred oily fish, which are all sources of omega 3 fats

For cooking at a high temperature, use virgin coconut oil or butter which is extremely stable.. For medium temperature cooking and on your salads, use plenty of extra virgin, unrefined olive, macadamia and avocado oils..

Healthy weight gain: Putting it all together 

A plate of food; egg salad with avocado, grated carrot, tomatoes, pickle.

In essence, your plate and day should look like this, but don’t obsess about it—just use as a gauge:

  • 40% veggies (carb and phytonutrients )
  • 10% whole fruit (carb and phytonutrients)
  • 25% high protein foods – meats (grass-fed ideally), veg, nuts/seeds, cheese/yoghurt
  • 10% healthy fat foods – from oils, seeds, nuts, oily fruits like avocado and from oily fish or game
  • 10% whole grains (carb)
  • 5% herbs (phytonutrients)

Additional tips for healthy weight gain 

Use Purition as a calorie top-up

Purition can help to to supplement additional essential fats, protein, fibre-rich carbohydrates and a plethora of phytochemicals to support all aspects of your biochemistry to gain weight in an incremental and sustained way. The blends won’t crash your blood sugar, nor do they contain any surprises in the form of hidden nasties. Include them in smoothies throughout the day to top up your calorie and macronutrient intake, alongside your breakfast or as a post-supper dessert or snack to help prevent overnight blood sugar crashes.

For more information, read our how to use Purition for weight gain guide.

Incorporate smoothies

Don’t fill up on fizzy drinks, coffee and other drinks with few calories and little nutritional value. Instead, drink smoothies or healthy shakes made with milk and fresh or frozen fruit, and sprinkle in some ground flaxseed or Purition. 

Watch when you drink

Be mindful that drinking fluids before meals can blunt your appetite. It may be better to sip drinks along with a meal or snack.

Make it all count

Snack on nuts, peanut butter, cheese, whole-grain crackers like oatcakes and avocados. Have a bedtime snack, such as a peanut butter and jelly sandwich, or a wrap sandwich with avocado, sliced vegetables, and lean meat or cheese.

Top it off

Add extras to your dishes for more nutrient dense calories — such as grated cheese in stews and scrambled eggs, and creme fraiche or avocado blended into soups. 

Treat yourself

Even when you’re underweight, be mindful of nutrient poor excess sugar and fat. An occasional slice of birthday cake or apple pie after your sunday roast is totally fine… totally! But mostly, try to keep other treats heavy on nutrients, such as homemade protein balls (you can add in your favourite purition flavour) , yoghurt & your favourite purition flavour, or homemade granola bars.


Exercise, especially strength training and rowing, can help you gain weight by building up your muscles. Exercise may also stimulate your appetite.

In health, Tanya x

Tanya Borowski | Dip CNM, mANP, IFMCP | Certified Functional Medicine Practitioner

Tanya holds a Diploma in Nutritional Therapy from the College of Naturopathic Medicine and completed The Institute of Functional Medicine certification in April 2016, and as such became one of only 25 fully-certified practitioners in the UK.

Tanya’s quest for knowledge has allowed her to partake in specialist training with some of the most respected functional medical doctors in their fields, ranging from leading coeliac and gluten sensitivity specialists such as Dr Tom O’Bryan to autoimmunity and thyroid specialist Dr. Datis Kharrazian, Dr. Mark Hyman and Dr. Jeffery Bland. She continues to travel to the United States at least twice a year to attend postgraduate training to further my knowledge and best help her clients.

Over the time that she has been practicing, Tanya has developed specialist interests and is most often consulted in the areas of autoimmunity, digestive complaints such as IBS, SIBO, non-coeliac gluten sensitivity, coeliac, and IBD, how to best assess for and manage thyroid health together with conditions of poor energy delivery such as CFS & fibromyalgia.

She runs her own Clinic and Wellbeing Store in Lewes, East Sussex. In addition to her one-to-one work in clinical practice,Tanya curates and hosts functional health 1-Day and 4-7 nights residential health retreats. Lecture’s for ION, on Female Health, Hormones and Gut health. She was also the co-writer of the revolutionary book The Clever Guts Diet with the world’s health guru Michael Mosley.     



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How to increase your protein intake

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