Between 2014 and 2015, two thirds (67%) of Australians were overweight or obese, an increase of 19% since 1995, and the latest report (2017) says Australia was crowned the fifth fattest nation in the developed world (OECD).
| Author: Anne Lecomber, BSc Human Nutrition, The University of Greenwich. Her website: Sugar Free Science. Nutrition news - without the sugar coating. |
It’s a global issue that is inextricably linked with other preventable health issues, with rising rates of obesity showing no signs of slowing. Whilst Governments across the world are scrambling to solve this growing and complex problem, people are trying to take matters into their own hands, searching for the perfect diet for weight loss and health.
Last year, the ketogenic diet was the most searched for diet on Google, leaps ahead of any other. Other fad diets have come, but never quite gone, but it seems the ketogenic diet (KD) with its seductive promises of quick solutions, will never be completely out of vogue.
KDs are very low carbohydrate, moderate protein, and high fat diets that induce a state of ketosis – a metabolic switch where the human body utilises ketone molecules for fuel as opposed to glucose. To flip this switch, carbohydrate intake needs to be low enough to deplete your muscle and liver glycogen stores, activating the utilisation of other energy sources, namely fat. An adaptation period that can take 3 days or longer. It does feel uncomfortable, all change does. To help bridge the gap and help adhere to the diet, a new keto supplement market has emerged.
There is no consensus on how many carbohydrates are needed to induce ketosis, with ketogenic diets typically viewed as eating below 50g carbohydrates per day. However, elevated ketones have been observed in individuals who eat between 58 and 192 g/day.
The definitive sign that you are in ketosis is the presence of ketones in the urine and blood, but beware; the urine strips you can buy online are not ideal for detecting ketones, as 3-β-hydroxybutyrate the most abundant of the ketones, cannot be detected using this method. Blood ketone monitors are deemed to be the most reliable method for objective ketone measurement.
Starvation: Extremely restricted calories or nutrients that lead to the the failure of bodily functions required for the maintenance of life. Prolonged starvation results in death.
Ketosis can be achieved through a fasting window under your control.
Getting the macronutrient composition of each meal just right is integral to a successful adaptation stage; too much protein can prevent ketosis, as 57g glucose can be created from 100 g dietary protein. This process called gluconeogenesis (GN), where the body produces glucose from non-carbohydrate derived substrates, can also be an issue for ketogenesis in people who are chronically stressed, as GN is a characteristic of the neuroendocrine response to stress and can lead to hyperglycaemia.
Flipping the script: Going from low fat to high fat. Giving up long held assumptions that have been hardwired into belief systems about Health will take time.
KDs are not a new concept. The KD was first used by doctors as a treatment for epilepsy in the 1920s, which was discovered to be more effective than fasting.
Fasting has been documented as a treatment for epilepsy since 500 BC which although effective at improving severity of seizures, is a risky strategy, especially in children. Scientists discovered that by eating a diet comprised largely of fats, a state of ketosis can not only be achieved, but maintained for longer. With the arrival of anti-epileptic drugs, the KD fell to the wayside, but made a dramatic comeback in the 1970s following the arrival of The Atkin’s Diet, heralding in a new weight loss era.
However, it was not until 2014 when Time Magazine blew the lid off the whole charade with their publication: Ending the War on Fat.
The flawed 1958 Ancel Keys study laid the foundation for modern dietary guidelines on fat – guidelines branded a “vast nutritional experiment” by Philip Handler who was the president of the National Academy of Sciences in the 1980s. Fats aren’t our enemy after all.
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| 1961: Vilification of Fat | 1984 | 1999 | 2014: Redemption |
Fasting is the Original Keto Diet.
Ketosis is a normal physiological response during starvation, which ensured our ancestors’ survival when food was scarce. Malnutrition aside, the problem with fasting is that people lose fat, but they also lose lean muscle mass. Nutritional ketosis prevents this as the diet allows an adequate intake of protein (~0.60-0.84g/kg of bodyweight/day).
Intermittent fasting (IF) has stages of shorter fasting periods of about 16 hours followed by refeeding periods over a defined period, typically just 8 hours, and is growing in popularity. There are two main variations: time restricted fasting where people fast for a few hours at a time, and alternate day fasting (24 hours fast followed by 24 hrs referring).
Fasting has a cultural and religious role beyond a biological necessity, and there are several different protocols. Some religions fast for just 24 hrs such as the Mormon religion, or every day for a month during daylight hours as seen with Islam. Religions that practice fasting believe it brings people closer to the deity they worship, but there is also an inherent belief that fasting cleanses the body as well as the spirit; trials of sacrifice, minimalism, and an escape from self-centred thinking. Whilst science can’t prove spirituality, there may be something behind the cleansing sentiment.
Weighing up the benefits of fasting
As a science-minded nutritionist, I resent the term ‘cleansing’, as it has become synonymous with the various cleansing and detox fads that are sold everywhere. Seeing as most of us have a perfectly good liver and set of kidneys that do the cleansing and detoxing for us, cleansing in a wellness context is absolute rubbish. Some studies have shown that IF could improve cognitive function, insulin sensitivity, longevity, morbidity, stress resistance, and cellular repair and regeneration mechanisms, where the latter would indeed help ‘cleanse’ our body of dying cells. However, most of the studies these claims stem from are from animal studies, and it has been suggested that the health benefits are derived from calorie restriction (CR) rather than fasting.
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In an 8 week randomised controlled diet intervention study, a group of obese women were divided into four groups: IF at 100% of basal energy requirements, IF at 70% of basal energy requirements, CR at 70% of basal energy requirements, and CR at 100% of energy requirements (control). Both IF groups lost significantly more weight than the other groups, but interestingly the IF group with no CR, had no improvements in metabolic and heart health biomarkers, suggesting that the benefits from health came from the CR. However, improvements have been seen in shorter fasting windows. For example: During Ramadan a fasting window of about 10 – 21 hrs is observed (depending on geographical location, due to differing sunset and sunrise times). Results from studies can vary though because of different fasting times and different foods available, and improved measurements may be confounded by people smoking less, as smoking is also prohibited during fasting hours. |
Even though this 8 week study suggests that IF is superior to CR diets for weight loss, the cumulative evidence from human studies indicate that weight loss is comparable between the two diets.
IF confers a surprising benefit to some people for weight loss, which is that some people find IF easier to adhere to because the duration of hunger is more intense, but shorter. People complain that when restricting calories daily, they feel hungry and are more prone to cravings, although this may be a sign that the calorie restriction is too severe. People want quick results, and think that eating less is more, when this can do more harm than good.
Weighing up the benefits of ketogenic diets
The KD was never designed to be a lifestyle, yet this is how it is sold online, along with a myriad of health benefits. Weight loss in the first few weeks on a KD can be spectacular, but this is mostly down to loss of water retention.
65% of glycogen is water, and when you use up your glycogen, the water goes too.
Studies have shown that KDs and CR diets are comparable for weight loss. When following people for a year on either a KD or low-fat diet, researchers found that the KD group had greater weight loss at 6 months, but at 12 months this difference was no longer apparent.
Many keto websites and blogs will list a health benefit, and quickly follow this with, “…one study showed…”. Medical News Today cites one study from 2004 as evidence that the KD is good for your heart.
Firstly, the study claims it was a long-term study, but 24 weeks is not long enough to determine if the diet is beneficial for heart health.
Secondly, the biomarkers measured - low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, and triglycerides – have come under scrutiny for their relevance in heart disease since this study.
Thirdly, the participants who were patients, were administered the diet on site, and because of this there was excellent adherence to a diet that was also calorie restricted. Patients lost a significant amount of weight (14.36kg average) therefore the improvements in biomarkers could be down to weight loss, not the KD.
Moral of the story: you need more than one study to support a claim.
A similar story is seen with keto and type 2 diabetes (T2D). Some studies have shown favourable outcomes including improved insulin sensitivity, and some T2D patients have been able to take less medication due to improved control of blood glucose, leading to patients ‘feeling better’ due to less medication-related side effects. Again, there is still uncertainty whether this is actually because of weight loss. KDs can also have a greater satiating effect due to higher fat and moderate protein intake, which in turn could lead to less snacking or binging.
There are clear medical reasons why clinicians might recommend a KD; epilepsy and other neurological conditions, polycystic ovary syndrome, and acne. Tentatively I mention that KDs could potentially stall the progress of some cancers. The reason for this caution is that there is a growing number of people foregoing medical treatment, believing diet can cure their cancer, often with fatal results. Diet cannot cure cancer which is a complex disease, but as scientists’ understanding of cancer cell glucose metabolism grows, diet therapy may help the prognosis of some cancers.
For weight loss, it is not a good long-term strategy. The KD is restrictive and hard to adhere to. Cramps, gastrointestinal issues, halitosis, headaches, irritability, nausea and hair loss are among a menagerie of normal, but usually transient symptoms of ketosis. It’s unsurprising then, that health professionals argue that a balanced, calorie restricted diet along with lifestyle changes is not only easier to adapt to and maintain but can have similar favourable outcomes. Even if you do decide to follow the KD, a return to normal eating is inevitable, and without new learned sustainable eating habits, there is a risk that the weight you lose could return. Conversely, positive results seen from a KD, could motivate you as you continue your weight loss journey.
There are variations; the ‘Cyclic Ketogenic Diet’ and the ‘Carb back-loading’ diet, are popular in the bodybuilding community, allowing people to follow the KD during the week and include a refeed day, or strategically consume most carbs post-workout respectively. Even these variations, have their own variations! There is a tonne of positive anecdotes to support these diet regimes, but they have not been well studied.
There is no evidence for the safety of keto diets long term, with the longest studies being 2 years in duration. Online you’ll see fanatical proponents and opponents downplaying and exaggerating the health risks respectively, but the reality is – we don’t know. There are risks associated with the KD if you don’t take a sensible approach. Some people think being on a KD is the perfect excuse to eat meat salads every day, but vitamin deficiencies can occur if a varied diet isn’t eaten. A high meat intake, especially processed meat, is also associated with a higher risk of heart disease and certain cancers.
Researchers are now suggesting that saturated fat may not be as harmful as we once thought, but it is still advised to keep saturated fat intake to 20g per day. Your fat intake on the KD should contain plenty of monounsaturated and polyunsaturated fats (oily fish, seeds, nuts, and plant-based oils). Avocados are a great food to include in the KD due to its high content of unsaturated fatty acids and fibre content of around 13g per avocado. Medium-chain triglycerides (MCTs), comprised of saturated fatty acids, are thought to confer some health benefits, and are thought to be healthier than animal-derived long-chain saturated fatty acids. MCTs are found in dairy products, but coconut oil is a popular, delicious source.
Fruits and vegetables need to be selected based on their carbohydrate status, and this can lead to a lack of fibre in the diet if fibre-containing foods are not sought after. Seeing as fibre has been shown to be protective for heart disease, T2D, stroke and colo-rectal cancer, it shines doubt on the purported benefits already mentioned.
You will see many keto champions saying the diet allows them to eat burgers and bacon every day, and it may be tempting to believe the plethora of anecdotal stories online, because then the diet doesn’t seem so restrictive after all. The evidence does not support this is healthy, and whilst people may claim they feel healthy now, non-communicable diseases can take 10 or more years to develop. We may not have any long-term evidence to support the safety of KDs, but there is plenty of evidence regarding fibre and meat.
Are either of these diets better than traditional calorie restriction for weight loss?
Short answer – no.
For weight loss, any diet will work if you are in a calorie deficit.
There really is no need to over-complicate matters. If your goal is weight loss and to keep the weight off, the diet you follow should be sustainable.
Longer answer - whilst we may not know if the health benefit claims for IF are solid, it seems to work for some people, but it isn’t for everyone, especially not for people like me who get super grumpy if they don’t have regular snacks. If you are eating nutritious foods on your non-fasting days, you aren’t fasting too much and too often then, and the weight loss is gradual, who is to say you should stop!
The KD isn’t magic and it is possible to put weight on following the keto diet if you are eating excess calories. It should only be used as a short-term strategy, with researchers recommending it should not be followed longer than 6 months.
You need to be organised and be prepared to plan the week ahead on either of these diets, and luckily there are apps available for both IF and the KD to make life much easier. It may go against the consensus of what constitutes a healthy diet, but that doesn’t mean that these diets can’t be approached in a sensible way. A nutritious, balanced diet should be the end goal.
With any major changes to the diet people should consult their GP. Nutritionists and dietitians can offer guidance on the risks, and dietary strategies you can implement to ensure that your health is not compromised.
With the growth in popularity of these diets, an increased focus on research is certain, but whether these diets will help curb the increasing rates of obesity remains to be seen. Research shows that despite many people being on a weight loss diet, diets aren’t working. This is because the causal map for obesity is immense and complex. For long-term sustainable weight loss, quite often a multi-layered approach is required that tackles the physiological, psychological, and environmental factors.
But, for the more dedicated, wilful dieter, these diets may prove to be a useful tool as part of a weight loss journey.
References
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