What is ketosis?
Ketosis is a metabolic state where your body favours fat metabolism over carbohydrates to generate energy for daily bodily processes and exercise.
Typically when carbohydrates are present in a diet, the body will create energy through a process called glycolysis. A glycolytic state differs greatly from a ketogenic state and has some key characteristics that ketosis challenges, a key difference between glycolysis and ketosis is insulin secretion.
When you eat carbohydrates they get converted into glucose and then they’re either used as energy there and then (if the energy demand at the time is high enough), stored as glycogen within the muscles or liver or stored as fat in adipose tissue.
A ketogenic diet differs from this, in that carbohydrate intake is minimal, whereas fat intake is very high, and makes up the bulk of your energy intake.
Fats are metabolized differently to carbohydrates and the presence of insulin secretion massively drops. When insulin is not present, a natural feedback system up-regulates glucagon secretion (1).
Glucagon – also produced in the pancreas – is peptide hormone that essentially has the opposing roll to storage hormone, insulin. Glucagon is responsible for plucking energy from existing stores: glycogen (stored carbohydrates) and lipids (fats) (2).
Increasing fat intake and dropping carbohydrate intake therefore requires the body to alter its metabolic state to efficiently yield energy from existing stores. Ketone bodies are also produced for the body to derive energy if carbohydrate intake is insufficient and fat metabolism enzymes also increase, setting the body up to be a ‘fat-burning machine’, utilizing fat as a primary energy source at rest and during exercise (2).
This metabolic adaption makes ketogenic diets popular with people who are looking to burn body fat and improve body composition. Many bodybuilders use ketogenic diets, combined with progressive calorie restrictions during contest preparation to drop those stubborn extra pounds of body fat.
How long does it take to get into ketosis?
The specific ratios of fat, protein and carbohydrates typically used to enter a ketogentic state vary from study to study. Often it’s recommended to split the aforementioned nutrients into a ratio of 70% fat, 15% carbohydrate, and 15% protein (3). I typically exaggerate this macronutrient intake even further when I use a ketogenic diet and often drop carbohydrate intake to 5%. I find this helps me get into ketosis faster.
When you change your eating habits to facilitate these macronutrient demands, you’re body’s metabolism will begin to change, which will bleed through to your body fat levels and body weight.
These metabolic and physiological changes that take place are not instant and are not the consequence of your first ketogenic meal. There is a delay where in which your body comes to realize that carbohydrates are no longer your primary energy source and that you’ll now need to shift from glycolysis (energy yield from carbohydrates) and adapt to utilizing fat as your main source of energy.
The big question often asked by those looking to immerse themselves into this fat burning zone is:
‘how long will it take to get into a ketogenic state?’
There’s often a slight variance from individual-to-individual in the time it takes to enter ketosis, some individuals report that they’ve got into ketosis in as little as 2-3 days, however 2-4 weeks is a realistic amount of time to get into ketosis.
Establishing whether or not you’re in a ketogenic state is usually determined by assessing serum concentrations of ketone bodies. Serum levels 0.5mM or over, combined with stable and low insulin levels would suggest that the metabolic shift has been made (2).
The most common method of tracking this is by using ketosis strips, which can measure these variables based on your urine profile.
Remaining in a ketogenic state is a consequence of dietary adherence, if you move away from the macro intake stated at the beginning of the article then you run the risk of reverting back into yielding energy mainly from carbohydrates.
How to induce ketosis?
Entering a ketogenic state is a desired effect for many people trying to lose weight or simply regain control of there health. Switching to a ketogenic diet, high in fat and incredibly low in carbohydrates is a strategy often used to eliminate the detrimental effects of sugar, which can include weight gain and chronic inflammation, both of which can cascade into further negative health issues. But how can you induce ketosis? What can you actively be doing day-to-day that will enable you to enter a ketogenic state.
Given that ketosis is a diet largely comprised of dietary fats, the first thing to consider is ensuring that your fat intake is high enough to signal to the body that this is your primary source of energy. Synergistically to this you need to flip the switch down on your carbohydrate intake, dropping it to a maximum of 15% of your dietary calories.
The combination of both these actions will signal to the brain that carb stores are depleted, but fat stores are abundant. This occurs as insulin levels drop and ketones bodies increase. This will alter the metabolic pathway of how you create ATP (energy), shifting the reliance onto ketone bodies as opposed to glycolysis (energy production via the breakdown of carbohydrates).
Some of the best foods, for me, to eat to enter ketosis are plant food sources naturally high in fats. The primary reason for leaning more towards plant based food is because they naturally contain a lot of antioxidants to safe guard your body from oxidative stress that we’re exposed to o a regular basis. Your fruit intake will also need to be reduced, so it allows you to bridge this antioxidant deficit effectively. Some good examples include avocadoes, almonds and olives (olive oil).
My carbohydrate intake – when I drop body fat using ketosis – mainly comes from vegetables, which includes broccoli, spinach and kale in abundance. Consuming vegetables when using a ketogenic diet provides you with valuable fibre, something else which is typically lacking on a ketogenic diet. To make the macronutrients even more favourable to my goal I also add some virgin olive oil to the vegetables after cooking them. Not only does this add some flavour, but also boosts your fat intake for that meal.
Studies also suggest that bouts of fasting also have a positive impact on inducing ketosis (3) and if you’re very dedicated to your goal, 24-48 hour fasting prior to starting your ketogenic diet is recommended.
Increasing your levels of physical activity also have a profound effect on inducing ketosis. This is because when you exercise, as you just begin to switch to a ketogenic diet, your body still have ample amounts of glycogen present within the muscles and liver. Exercising gets to work at depleting this stores, which in turn opens the door for the liver to create ketone bodies to often the energy expenditure (4).
Ketosis diet supplements
When a diet is reliant on restricting an entire macronutrient and hiking up another macronutrient it’s inevitable that supplements will play an influential role in the end result and sustainability. As such it’s important you stick with an effective ketosis supplementation strategy. Here are some of my ‘go to’ supplements when I used a ketogenic diet:
When you eliminate fruit intake from your diet it can often lead to vitamin deficiency. Vitamins are essential for numerous bodily functions and energy yield and as such, a deficiency can lead to unwanted symptoms that typically cause people to abandon the entire diet. This can include severe tiredness and even food cravings.
A good-quality multivitamin can help combat this and also provide support against oxidative stress.
Similar to the case of supplementing with a multivitamin, ketosis can also lead to a mineral deficiency. Often people will lose a lot of their electrolytes because ketosis can make you thirsty, therefore supplementing with magnesium and potassium is also going to be beneficial.
L’carnitine is an amino acid that acts as a shuttle for fat to enter cell in order to be metabolised. Supplementing with l’carnitine will naturally increase the potential for more fat to be shuttled into the cells of the body and used as energy.
Low carb protein shake
A lot of protein shakes, especially mass gainers, contain simple sugars to both boost calorie intake and increase insulin secretion. When you’re using a ketogenic diet, simple sugar needs to be restricted, pretty much completely, therefore if you often use protein shakes you’ll need to get yourself a low/no carb alternative.
Ketosis meal plan
Piecing together a ketosis meal plan allows you to remain focused and get organised with your meal preparation. A big part of effectively transitioning and remaining in a ketogenic state is preparation, given how rigid the macronutrient ratios are. This is often the case with a lot of dieting strategies, you become most vulnerable to straying off-track when you have no food to hand that meet your requirements.
The ketogenic meal plan below is a sample ‘day in the life’ of when I recently used a ketogenic diet for 1 month to shred some fat:
Breakfast: 4 whole eggs, half an avocado and a bulletproof coffee*
Meal 2: Tuna salad (1 tin of tuna with as much green as you want, drizzled in extra virgin olive oil)
Post-session: Low carb whey shake with cream and a handful of almonds
Meal 3: 2 salmon fillets with broccoli and – again – drizzled in olive oil
Meal 4 (before bed): 2 eggs with full fat cottage cheese
*Bulletproof coffee – 1 shot of coffee with 1 tablespoon of grass-fed butter and 1 teaspoon MCT oil
As mentioned, this is just a sample day, however following a diet such as this will get you into ketosis fast!
In terms of body fat reduction, this diet took me from around 12% to 7%, which is very low and for the purpose of a photoshoot. A body fat reading this low isn’t necessarily optimal; a healthy reading for women is between 21%-24%, for men this should range from 18%-24%.
If body fat becomes excessive low it can lead to some health complications including fertility issues with women and loss of bone strength.
Isn’t eating a lot of fat bad for you?
Studies suggest that ketosis is beneficial for weight loss, but does this come at any kind of cost to the body?
Many people are initially skeptical of ketogenic diets and concerned about the high-fat intake and its influence on cholesterol and heart disease.
Social perception of fat intake in the diet was somewhat skewed by dated literature, this led to a rise in popularity of low fat diets in the 80s and 90s. But what does the research say? Are high fat diets bad for you?
A study conducted by Dashti et al (5) in 2004 examined both the long-term effects of a ketogenic diet for weight loss effectiveness and general health. The study – using a testing group of 83 obese patients – placed subjects on a ketogenic diet for 24 weeks, examining both key body composition variables: body mass index (BMI) and body weight, along with blood bio-markers, including: low density lipoproteins (LDL) cholesterol, high density lipoproteins (HDL) cholesterol and triglycerides.
Subjects induced ketosis by adhering to the strict macronutrient intake: 30g of carbohydrates, 1g/kg body weight protein, 20% saturated fat, and 80% polyunsaturated and monounsaturated fat. The results from the study signal that ketogenic dieting is not only a beneficial long-term dieting strategy for weight loss (with significant decreases in both body weight and BMI), but there was also a positive impact on bloodwork, with HDL increasing, LDL decreasing and total triglycerides decreasing.
Fuehrlein BS et al. (6) went a step further and set out to understand the influence of saturated fat and polyunsaturated fat for inducing ketosis and the effectiveness and health impact when you vary the ratio of these two types of fat. The study split the pool of subjects into 3 groups, all of which adhered to the macronutrients of 70% fat, 15% carbohydrate, and 15% protein.
Group 1: 60% Saturated fat; 15% polyunsaturated fat
Group 2: 15% Saturated fat; 60% Polyunsaturated fat
Group 3: 25% Saturated fat; 25% Polyunsaturated fat
The study found that a ketogenic diet favouring polyunsaturated intake induces a more effective ketogenic response, improves insulin sensitivity without negatively impacting low-density lipoprotein cholesterol (LDL cholesterol). This was in contrast to the high saturate fat group, who experienced an elevation in LDL cholesterol.
These findings suggest that inducing ketosis favouring polyunsaturated fat intake is not only more effective for weight loss, but also improving your lipid profile.
Sports performance and ketosis
Carbohydrate loading has become as much of an integral part of competitive endurance athletes routine as the training itself. Athletes typically ‘pre-load’ and replenish carbohydrates prior to and after races/training with the understanding that it’s required to fuel the grueling training and competition that they will endure.
Does this age-old practice hold true under the scrutiny of modern-day research and what about other athletes, who rely on other physical attributes, such as strength, power and speed – do these athletes also need a carbohydrate-rich diet?
Endurance exercise and ketosis
Although carbohydrates are a readily available fuel source of the muscles, you can only store around 2000 calories of carbohydrates, in the form of glucose and – primarily – glycogen, which is stored in the muscles and liver. Whereas fats are a relatively abundant source of energy. This has led to the use of ketogenic diets in endurance sports being researched, scrutinized and heavily debating among academic circles and endurance enthusiasts.
Endurance sports are often categorized as long-distance, steady state sport/exercise. However the reality of sports such as cycling, triathlons and long distance running etc is that they require bouts of more intense energy output, among steady-state exercise. As such energy systems necessary can fluctuate at different points of a race, when discussion optimising sports performance, carbohydrate intake is necessary to trigger anaerobic glycolysis to facilitate these short outbursts of energy, that require energy where oxygen supply is low.
The impact of ketosis and the transitioning time into ketosis should also be considered when you discuss optimizing your training regime for endurance exercise/sport. Depending on dietary and food timings, ketosis can take anywhere from 3-14 days to fully induce. This transition period into ketosis can be taxing on the body as carbohydrate intake has been significantly lowered and the metabolic environment is not yet designed to fully support fat as an effective and primary energy source.
The argument for utilizing ketosis effectively for endurance events is that fat reserves are the primary energy source over such long distances. As such, creating a metabolic environment that is adapted and efficient to using fats an energy source would serve as a benefit to factor in.
A study by Volek et al found that a long-term ketogenic diet led to a huge boost in fat-oxidation rates, compared with subjects who used a high-carbohydrate nutrition plan, whereas muscle glycogen utilization remained uninfluenced. Therefore it can be hypothesized that utilizing ketogenic dieting protocol in the run up to an endurance event, combined with pre-loading on carbohydrates may have benefits in optimizing by energy metabolism and availability (REF).
Power sports and ketosis
The difference between the energy systems necessary to compete in endurance events and strength/power events is vast. The energy system needed to perform in power sports is the creatine-phosphate energy pathway, which comes into play so rapidly that oxygen presence and an energy abundant fat store such as fat are not necessary. Paoli A, et al demonstrated the influence of a ketogenic diet for strength athletes in his 2002 examining the effects on gymnasts (6). The study found that athlete’s experienced no dip in strength levels after 30 days of ketogenic dieting, whilst body weight reduced and overall body composition improved.
Furthermore, studies suggest that ketone bodies are anti-catabolic and muscle sparring (7), typically an advantage for athletes who participate in strength and power sports.
It is however suggested that there may be benefits for strength/power athletes from supplementing with creatine during a ketogenic diet. Creatine is made up of amino acids arginine and methionine. On a true ketogenic diet, protein intake is typically reduced slightly to make the Fat:Proteins:Carbohydrates ratio favourable to the shift in energy reliance. Therefore it’s recommended that strength/power athletes supplement with creatine whilst using a ketogenic diet to maximise relevant energy output/resynthesize.
1. Roger H Unger, MD. Glucagon and the Insulin:Glucagon Ratio in Diabetes and Other Catabolic Illnesses. Diabetes 1971 Dec; 20(12): 834-838.
2. Anssi H Manninen. Metabolic Effects of the Very-Low-Carbohydrate Diets: Misunderstood “Villains” of Human Metabolism. J Int Soc Sports Nutr. 2004; 1(2): 7–11.
3.Longo VD, Panda S. Fasting, Circadian Rhythms, and Time-Restricted Feeding in Healthy Lifespan. Cell Metab. 2016 Jun 14;23(6):1048-59.
4.Féry F, Balasse EO. Response of ketone body metabolism to exercise during transition from postabsorptive to fasted state. Am J Physiol. 1986 May;250(5 Pt 1):E495-501.
5.5. Dashti et al. Long-term effects of a ketogenic diet in obese patients. 2004. Exp Clin Cardiol. 2004 Fall; 9(3): 200–205.
6.Fuehrlein BS. Differential metabolic effects of saturated versus polyunsaturated fats in ketogenic diets. J Clin Endocrinol Metab. 2004 Apr;89(4):1641-5.
7. Anssi H Manninen. Very-low-carbohydrate diets and preservation of muscle mass. Nutr Metab (Lond). 2006; 3: 9.
8. Volek et al. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism
Volume 65, Issue 3, March 2016, Pages 100–110.