Ketogenic Diets: Do They Really Work?

ketogenic diets

Low carb, high fat (LCHF) diets still remain on trend, however a popular variation exist amongst the fitness crowd, known as the ketogenic diet. But does this diet live up to the hype?

What is a Ketogenic Diet?

A KD eating pattern is very low in carbohydrates and moderate in protein, however unlike most low carb eating plans (e.g. Atkins), the ketogenic diet has a high percentage of total energy (kilojoule) intake from fat.

As fat is the main source of energy being consumed, the body must then use this (that is, break it down) as its main energy source or ‘fuel’. When dietary fat is metabolised for energy, by-products called ‘ketone bodies’ (molecules that are made by the liver from fatty acids) are produced which are used up by the body’s tissues, muscles and the brain. This process is known as ‘ketosis’.

The body can enter ketosis during times of severe energy restriction (such as during fasting or starvation) or prolonged intense exercise, or when carbohydrate intake is reduced to around 50g per day, or less – the equivalent of around two slices of bread, and a banana.

But the difference between a LCHF diet and a true KD is that the latter remains proportionately lower in carbohydrates – 20-50g per day, and less than 10 per cent of total energy, keeping the body in a state of ketosis, even if total energy intake increases.

What about weight loss?

Following a KD will undoubtedly result in short-term weight loss, which probably comes down to a reduction in total energy (kilojoule) intake, the depletion of liver and muscle glycogen stores and associated water, and a reduced appetite (which is a side-effect of metabolising ketones, and also due to satiety associated with eating foods containing fat and protein).

But the key to maintaining a healthy weight in the long-term is an eating pattern that is sustainable over time – that is one you can stick to! With this in mind, dietary recommendations should always be tailored to an individual – as everyone is unique, and what works for one person, may not work for another. That is, there is no one-size-fits-all approach when it comes to achieving and maintaining a heathy weight.

Limitations of the ketogenic diet

A strict KD is undoubtedly difficult to stick to because it drastically reduces the intake of a number of food groups, including fruit and vegetables, dairy foods, and grain foods. This means carbohydrate-containing foods, such as breads, cereals, rice, pasta, legumes, fruit, and starchy vegetables (like pumpkin, peas, and potato) must all be limited.

In fact, the 20-50g of carbohydrates allowed in a KD is equivalent (in carbohydrate terms) to just a small tub of yoghurt, an apple, and half a medium potato over a day. So, using fruit as an example, following a KD would likely mean limiting fruit to only one serve a day, or eating it in place of other nutritious foods like vegetables, dairy foods, and grains[vi]. This requirement to strictly limit certain foods makes it near impossible to meet nutrients needs without supplementation.

With limited carbohydrates, a KD is very low in fibre, so can cause gastrointestinal symptoms like constipation. It may also increase the risk of bowel cancer in the long-term. The KD can also present challenges relating to the social aspects of eating, such as enjoying food in family and social situations.

Any side effects?

Short-term side effects of ketosis can include fatigue, bad breath, nausea, constipation, and headache.

What does the science say? Proven for medical conditions ONLY

Research supports a role for the KD as a medical intervention for some cases of epilepsy (that is, when seizures are intractable), particularly in children.

KDs have been used to treat epilepsy in children since the 1920s, and are only recommended to be trialled with the full support of a multidisciplinary medical team, including dietitians, neurologists, nurses, pharmacists, and social workers. A dietitian’s support is vital, as a KD is very restrictive, with foods like starchy vegetables, dairy foods, fruit, and grain foods limited – making it difficult to meet long term nutrient needs for key vitamins and minerals, such as folate and calcium. As such, nutrient needs must be carefully monitored.

There is growing interest in the effect of a KD in patients with cancer, particularly brain cancer. Tumour cells have an increased reliance on glucose, and many cannot use ketones effectively, so the hypothesis is that disrupting cellular metabolism may improve current treatments. Additionally, some researchers propose that ketones may be toxic to some cancer cells. While the current research and preliminary results from clinical trials suggest a KD may show anti-cancer and neuroprotective effects, there are various limitations to consider. Much of the current evidence is observational, undertaken in small populations, and in animals, so further research is needed before strong conclusions can be drawn.

The bottom line

Despite many books and websites proposing a KD for a variety of health benefits, the evidence for these in healthy individuals is currently limited to therapeutic uses in specific conditions. In reality, the diet is backed by very limited evidence in healthy individuals.

Though it may offer some metabolic benefits when followed in the short-term (a few months), and pose as a novel treatment for certain medical conditions, a KD isn’t recommended for the general population, as the long term efficacy and safety of the diet are unknown, having only been studied in the short-term.

And as always, for people who are confused about what they eat or want more specific advice, DAA recommends seeking this from an Accredited Practising Dietitian (APD). And if you choose to undertake a KD, this should be done under clinical supervision – with the guidance of a health professional, such as an APD.

Top 3 things to consider before starting a ketogenic diet:

1. You’ll be missing out on some seriously healthy foods
A ketogenic diet is based around a very low carbohydrate diet, which means nutritious foods like vegetables and fruit, wholegrains and dairy foods will need to be limited. In fact, the 20-50g of carbohydrates allowed in a ketogenic diet is equivalent (in carbohydrate terms) to just a small tub of yoghurt, an apple, and half a medium potato over a day.

2. It might affect your gut health
As well as filling us up, fibre from fruit, vegetables, legumes and wholegrains is vital for a healthy gut – such as to support the growth of ‘good’ bacteria and to keep the lining of the bowel healthy. On average, we eat only half the recommended daily amounts of at least 25g of fibre for women and 30g for men – and being on a ketogenic diet will make it harder to meet these targets.

3. You may find it hard to stick with
The best ‘diet’ is one that ticks off all your nutritional needs, fits with your lifestyle, and that you enjoy. If you get these right – you’re onto a winner over the long-haul! Many studies show those on a ketogenic diet find it difficult to sustain, due to its restrictive nature (which can also make family meal times and outings with friends more complicated).

For more information, visit the Dieticians Associations of Australia website.

Get Glowing Winter Skin

kathleen's skin

WINTER CAN WREAK havoc on your skin, but you don’t need to flake out just because the temperature’s
dropping. Here are my top tips to get healthy, glowing skin all winter long (in between facials and without injections).

Indeed the largest organ in the body. The skin’s epidermis (outer layer) protects your body from invasion and helps seal in moisture. The next layer, the dermis, is where collagen and elastic tissues lie, giving our skin it’s structure and support.

Why so dry?

Dry skin generally has low levels of sebum (oil) and water and is often characterised by a rough and flaky appearance. Most dry skin results from environmental factors including exposure to cold weather with low humidity levels, dry air from indoor heating and hot water from bathing.

Skin Salvation: we all know the importance of exfoliation, which this should be done at a minimum of once a week to get rid of dead skin cells and promote cell renewal. Another ritual is dry body brushing with a loofah or exfoliating gloves just before showering, followed by applying a good rich moisturiser containing humectants (substances that attract and retain moisture) is effective. Look for ingredients such as panthenol (a form of vitamin B derived from plants), shea or cocoa butter.

dry body brush


Feed your Face

skin foods


The old adage ‘you are what you eat’ holds true when it comes to your skin. Healthy skin can be encouraged by including certain foods in your diet, such as eating plenty of fruit and vegetables – a potent source of antioxidants to help fight free radicals which cause skin damage and skin ageing.

Eating plenty of foods that are rich in omega-3 will also help keep the skin cells lubricated. Foods such as salmon, walnuts, olive oil, soybeans and ground flaxseeds are also excellent sources. See my recent post on the top foods for a glowing complexion.


Although most dermatologists would argue that the skin’s condition is determined specically by external factors, almost all nutritionist would agree that drinking plenty of water for overall health and wellbeing is highly recommended. We tend to forget to drink water during the colder months and don’t realise that dehydration can also occur in the winter time. So quench your thirst with water first to stay hydrated.

Quick Tips:

USE WARM WATER for bathing instead of steaming hot water and take shorter showers.

REPLACE REGULAR SOAPS with soap-free substitutes with moisturisers that won’t wash away the body’s own oils.

PAT DRY with a towel to remove excess water. Never rub dry.

APPLY A MOISTURISER while your skin is still damp to seal in the water.

IRRITATED SKIN. If your skin is seriously irritated or dry, simple is always best. Opt for fragrance-free preparations developed specifcally for sensitised skin, and avoid over exfoliating.

What’s your winter skin care routine. Please share.


Feed Your Face

skin foods

WANT more radiant, healthy-looking skin? THEN FEED IT! Here are the top 10 foods to turn back the clock.

Yoghurt contains live probiotics, such as acidophilus, help to aid digestive balance and maintain a healthy gut flora. In other words, when your gut is working right, it can better absorb all of the nutrients your skin needs from your diet so your skin receives more nutrients it needs to be healthy. To make yoghurt a staple in your daily diet, try replacing mayonnaise, cream, salad dressings, or whip up a fruit yoghurt smoothie. Just be sure to choose a natural, Greek and low-sugar varieties, since sugar can aggravate inflammation (ageing).

Tomatoes are rich in age-defying ingredient lycopene – a the natural pigment that makes tomatoes red can help protect against sunburn and skin ageing caused by sunlight exposure. To reap the most benefits, lycopene is best absorbed by the body when it has been cooked or processed. So eating tomato paste, tomato soup or canned tomatoes is likely to be more effective than just eating raw tomatoes when trying to safeguard your skin against getting fried.

Carrots have long been touted as the best vegetable for protecting the skin. Why? They are chock-full of beta-carotene (converted to vitamin A in the body), which and is essential for proper cell growth and repair cell – that means fewer dead cells to combine with sebum and clog pores. How’s that for a natural exfoiliation. Beta-carotene also acts as an antioxidant to mop up harmful free radicals, helping to prevent pre-mature ageing. Toss carrots into a stir-fry, enjoy them raw as a snack with hummos, or grate them into salads or wraps.

Water. Remaining properly hydrated is one of the best things you can do for a glowing complexion, since even mild dehydration can result in the skin looking and feeling parched, too. Caffeinated beverages, sugar-sweetened drinks and juice don’t count – it has to be water! Water hydrates skin cells, allowing efficient absorption of nutrients and removal of toxins.

Blueberries. Compared to other commonly consumed fruits, blueberries are the highest-ranking food source of skin-loving antioxidants, which target DNA-damaging free radicals, reducing skin cell damage and premature ageing. While remaining low in calories and high in fibre, blueberries are the ultimate waist-friendly snack to enjoy between meals.

Dark Chocolate. As if you needed another reason to get your chocolate fix! dark chocolate is rich in flavonoids – a type of antioxidant that helps to equip the skin with a stronger defense against wrinkle-causing UV rays. Chocolate also makes you feel happy – when you eat it, the brain releases endorphins, your body’s natural feel-good hormones. And when you feel good, you look good.

Citrus fruits. The citrus family is brimming in Vitamin C, which not only is good for warding off the sniffles, but also a prime skin-care ingredient which smoothes out wrinkles by stimulating the production of collagen – the skin’s support structure. The more collagen you have, the less creased your skin looks. Research also shows that eating more vitamin C-rich foods may promote the repair of DNA that’s been damaged by UV rays. Beyond citrus fruit, strawberries, kiwis, tomatoes and capsicum are pack a C punch.

Salmon offers a whole heap of omega-3 fatty acids to keep cell walls supple, allowing water to better penetrate the epidermis (top layer of the skin). And since each skin cell wall influences the cell’s ability to hold water, having a healthy barrier provides you with plumper, well-hydrated skin. Research also shows that getting too little omega-3’s may contribute to inflammatory disorders like eczema and psoriasis. Other omega-3 rich fish include tuna or mackerel. Aim to eat two servings of fatty fish each week. If fish isn’t your thing, consider adding flaxseed oil to the dressing, or snack on walnuts to quench your skin.

Almonds are packed full of vitamin E, another powerful antioxidant that helps to protect skin cells from UV light and other environmental factors that generate cell-damaging free radicals. Almonds are also rich in monounsaturated fat, the healthier type of fats known for lowering cholesterol and keeping cell membranes strong and intact – crucial for keeping skin youthful.

Brown rice. Check the packaging of your skin products and you’re likely to see ceramides in the list of ingredients. These lipid molecules, which help your skin maintain its moisture, are also founds in wholegrain brown rice. As opposed to refined grains, such as white bread, pastas, and cakes, eating wholegrain don’t cause rapid spikes in blood sugar. Too much insulin may effect sebum production (a type of oil produced in the skin’s gland), which can cause breakouts. Other wholegrains include rye, corn, oats and barley. Aim for 3-4 serves a day.