Debunking 10 common myths about the keto diet
This time of year, many people are feeling bloated and overweight after indulging in too many holiday treats. The average weight gain over the Christmas period is half a kilo (one pound), but some of us may have indulged a tad more than others.
I stuck to my usual diet, more or less, but I have to admit to eating more of those foods than I would usually eat. Now I'm looking to drop a couple of kilos, some of which accumulated over the last year. If this is you too, then I'd like you to introduce you to the ketogenic ('keto') diet, why it's a good idea for cancer patients and survivors, and debunk some myths that surround the diet.
On a keto diet, you reduce your carbohydrate intake to 5% of your total calories. Protein is usually between 20% and 35% of your calories, and fat represents the rest. The idea of the diet is to switch from using glucose (derived from carbs) to using ketones (which the body synthesises from fat) for energy.
For anyone who has cancer, and for those who have had it and want to avoid it recurring, a keto diet can be really helpful. Most cancer cells prefer to use glucose for energy. We know this as the Warburg effect. Reduce the amount of glucose in your diet, and you cut off their source of energy.
You can successfully lose weight on a keto diet. Excess weight is a risk factor for cancer starting or returning. Cancers known to be affected by excess weight include colorectal, breast, uterine, oesophageal, kidney, gallbladder, liver and pancreatic cancers, and researchers attribute between 4 and 8% of all cancers to obesity (1).
There are many myths surrounding keto, and I'd like to explore and debunk 10 of them.
Myth 1: It's all protein and no vegetables
This myth came about because of the original Atkins diet, which was very restrictive and encouraged people to eat eggs and bacon, meat and fish, and butter, cheese and cream, with virtually no vegetables. It was effective because it was incredibly low on carbs. It also sends you into ketosis. But most people found it difficult to follow. Today, we would call this carnivore.
A keto diet doesn't necessarily have to contain meat, so you can adapt it to a vegetarian and even a vegan diet. If you're sensitive to dairy, it's possible to make it dairy-free too. Just avoid bread, pasta, rice, grains, legumes and starchy vegetables. (If you can't live without bread, there are keto breads available, and you can easily make them yourself. There are also some tasty low carb seed crackers to buy and make yourself.)
An ideal way to start a keto diet is to take your protein, add some green, leafy vegetables and add some good fats. Good fats to include are olive oil, avocados and avocado oil, coconut oil, and butter, eggs and cheese if you are not vegan. There's no need for fancy recipes unless you want to cook something special.
Myth 2: Keto is just for weight loss
It's certainly true that keto can be a good way to lose weight. The high fat slows the passage of food from the stomach to the intestines, so you feel full for longer after a meal.
But for some people, this signal is weaker than others. They will find it easier to overeat on a low-carb diet, just as they do on a low-fat diet.
So, you do also need to reduce your kilojoule (or calorie) intake. The easiest way to do this is to use an app that tracks your food intake and your macronutrients. Macronutrients are kilojoules (or calories), carbohydrates, fats and protein. There are plenty of them out there. I'll include the ones that I use in the Resources at the end.
Myth 3: A low-carb diet causes ketoacidosis
Ketoacidosis is a rare medical condition that can be very serious. It usually happens in Type I diabetics who don't take enough insulin. It can also occur in Type II diabetics on certain medications, like SGLT-2 inhibitors, although it is quite rare. But one case study reported a diabetic man on an SGLT-2 inhibitor who had been following a low-carb diet, who developed ketoacidosis (2).
Ketosis is different. It's a perfectly natural metabolic state, where the body adapts to burning fat for energy, creating ketones. Ketones can fuel our bodies just as well as glucose, without causing rises in blood sugar levels and insulin spikes.
Myth 4: Keto raises your risk of heart disease
This is a big worry for many people. It seems logical that if you eat more fat, it will end up in your arteries. This was the reason that health authorities all over the world pushed a low-fat diet for so long. Unfortunately, heart disease has rocketed since then, as a diet high in carbs, particularly refined carbs, is more likely to be the culprit rather than saturated fats (3).
There are many factors that contribute to heart disease, including inflammation, genetic factors and metabolic conditions like diabetes. A good quality keto diet is not usually one of them.
Myth 5: Keto increases cholesterol levels
For most people, a keto diet will improve your lipid profile by reducing triglycerides and increasing HDL, commonly called 'good cholesterol'. Keto usually also improves the particle size of LDL cholesterol. LDL can be large and fluffy, or small and dense. The small, dense particles are the ones that can cause atherosclerosis. Usually low-carb diets push the particles towards being large and fluffy (4).
For a minority, they may find that their LDL cholesterol levels increase. If this happens, you have 3 choices:
Decrease your saturated fat levels by reducing those extras that so many keto dieters love, like adding cream or butter to coffee, using lots of rich sauces, eating lots of cheese, and adding cream to cooking. Instead, increase the amount of monounsaturated fats, like olive oil and avocado, and eat more nuts. That way, you should be able to maintain the benefits of a keto diet.
Eat more fibre. High fibre diets lower LDL cholesterol (5).
If all else fails, try cycling higher-carb days with lower-carb ones. Or switch to a higher level of carbs and see whether that helps.
Myth 6: Keto causes nutrient deficiencies
A properly constructed keto diet is probably more nutritious than a high-carb diet.
Eggs are the mainstay of many keto dieters, and they contain virtually everything you might need to stay healthy.
Rather than eating pasta, you can use zoodles (spiralised zucchini or courgettes). There are also some good soy pastas available.
Instead of rice and couscous, finely chopped cauliflower or broccoli (or a mix of both) works well.
Roast vegetables such as radishes and kohlrabi to replace roast potatoes. They're really tasty. Lightly cooked zucchini (courgette) is a great stand-in for boiled potatoes in dishes like potato salad.
It's true that keto doesn't include fruit, except for a few berries. But fruit is not the only source of vitamin C. Brassica vegetables like cauliflower, broccoli, wombok (Chinese cabbage), cabbage, Brussels sprouts and cooked kale are excellent sources too.
Some of the other low-carb vegetables include artichokes, asparagus, avocado, baby corn, bamboo shoots, bean sprouts, green beans, Asian vegetables, red and green capsicum (bell peppers) (in small quantities), celery, chicory (endive), cucumbers, fennel, leeks (in small amounts), lettuce, mushrooms, snow peas (mange tout), spinach, squash, tomato, turnip, water chestnut and watercress. So, there is no shortage of variety, and you can still eat a rainbow and get your 5 servings of vegetables a day.
Fat-soluble vitamins like vitamins A, D, E and K are abundant on a keto diet, whereas they are often deficient in a high-carb diet.
Myth 7: Keto diets put a strain on the kidneys
This is based on the premise that keto diets are high in protein. But they are actually moderate in protein. But even if you overdo the protein, unless you have end-stage kidney disease and are close to needing dialysis, your kidneys should be able to manage easily.
If you have severe kidney disease and your doctor has told you that you need to limit your protein intake, of course you should follow their advice. But that doesn't mean you can't follow a low-carb, high-fat diet.
If you're diabetic, the drop in blood sugars on a keto diet could protect your kidneys from damage from glucose, avoiding a common issue in diabetes.
Myth 8: Keto diets make you low on energy
If your body has been used to running on carbs, then reducing them might affect your performance in the gym until your body has adapted to running on fat (or ketones, which the body makes from fat).
Once your body has adjusted to ketones, which can take up to a couple of weeks depending on your metabolic fitness, most people feel as good or even better than they did before.
Initially, you may experience symptoms that feel like the flu. Keto flu is a real thing. Because insulin levels drop, the kidneys respond by excreting more sodium. Less sodium in the body means that the kidneys excrete more water. The solution is to add a little salt to your water and increase the salt on your food too.
Myth 9: Keto makes you constipated
Let's first define what constipation is and isn't. The definition of constipation is a decrease in bowel movements that makes you uncomfortable and interferes with daily life. Symptoms include bloating, passing wind, abdominal pain, blood in your stools, and straining or pain on emptying your bowels. Doctors define it as emptying your bowels 3 or fewer times a week.
Just because you aren't visiting the bathroom as often doesn't mean that you're constipated unless you are finding it uncomfortable. Remember that you aren't consuming as much bulk on a keto diet, so you have less waste to remove.
Initially, the sudden reduction in fibre might cause your digestive system to slow down. Try to ensure that you get at least 25g of fibre a day if you're female and 38g a day if you're male, preferably from proper foods, rather than supplements. A helpful food to include is avocado: a 150g (5 oz) avocado contains about 10g of fibre, as well as a useful 23g of good fat. Nuts and seeds are also excellent additions, and make sure you eat enough of the low-carb vegetables listed above.
Dehydration is another cause of constipation. Increase your water and your stools will soften and be easier to pass.
Myth 10: Keto diets can cause osteoporosis
Many cancer patients have used drugs that increase the risk of osteoporosis, like corticosteroids. And those on hormonal treatments are at higher risk of osteoporosis as well.
Scientists used to think that a diet low in carbohydrates and higher in protein would cause the blood to become acidic, which would then leach minerals like calcium from our bones and weaken them.
It's important to understand that our body tightly controls the pH of our blood, so there's no chance of our blood becoming acidic. In fact, if it became acidic, we would quickly die.
Far from causing osteoporosis, research shows that higher protein diets increase bone mineral density (BMD) and significantly reduce the chance of hip fractures (6).
Helpful hints and resources for would-be keto dieters
It's really helpful to use a good app to track your macros (calories, fat, protein and carbs). My personal favourite is Carb Manager (I don't have any affiliation with them). I like it because it makes my life easy.
Although it's an American app, it has lots of international foods in its database, and I can easily add them if they aren't there.
I can scan a barcode, and it will usually find the food and track it. The tracker is available on the free version.
I have the Premium version, which I find to be relatively cheap compared with some apps, and that means I can add my own recipes to it.
It will even import recipes from elsewhere from the URL.
And it has a lot of great recipes in it (both keto and low carb) that are all macro-counted to help with your choice.
You also have access to a community of like-minded people and heaps of helpful articles. Here's one to start you off - https://www.carbmanager.com/article/x1kx9beaacmaxluv/ultimate-guide-to-keto
Other people prefer alternative apps like Diet Doctor, which certainly has some great recipes and some great information, although it seems to be a lot more expensive than Carb Manager. Alternatively, you might want just a simple tracker that's free. This link can help you find the best ones around - https://www.sydney.edu.au/news-opinion/news/2016/02/11/experts-rank-the-best-apps-for-weight-loss.html
Looking for tasty, easy recipes? My favourite site is https://madcreationshub.com/recipe-index/ . They are based in Australia, but they write their recipes for an international market, so they include easy to find items and they use both Australian and US words for everything. Very few of the recipes take longer than 30 minutes to make, and they all show the macronutrients.
If you think a keto diet is too strict for you, then perhaps a low carb high fat one would suit you better? It offers similar benefits to keto; you can use it to lose weight and help to balance your insulin and blood sugar levels. Both will help you fight cancer starting or returning. The low carb high fat option is also available in all the apps that cover keto diets.
If cutting back on carbs doesn't appeal to you, I cover some other cancer-focused diets in my book. It's possible that one of those will be a better fit for you.
References
Pati S, Irfan W, Jameel A, Ahmed S, Shahid RK. Obesity and cancer: A current overview of epidemiology, pathogenesis, outcomes, and management. Cancers. 2023;15(2):485. doi:10.3390/cancers15020485
Mung SM, Fonseca I, Azmi S, Balmuri LMR. Prolonged diabetic ketoacidosis due to SGLT2 inhibitor use and low‐carbohydrate diet. Practical Diabetes. 2023;40(2):24-27. doi:10.1002/pdi.2446
Gershuni VM. Saturated fat: Part of a healthy diet. Current Nutrition Reports. 2018;7(3):85-96. doi:10.1007/s13668-018-0238-x
Gjuladin-Hellon T, Davies IG, Penson P, Baghbadorani RA. Effects of carbohydrate-restricted diets on low-density lipoprotein cholesterol levels in overweight and obese adults: A systematic review and meta-analysis. Nutrition Reviews. 2018;77(3):161-180. doi:10.1093/nutrit/nuy049
Anderson JW, Davidson MH, Blonde L, et al. Long-term cholesterol-lowering effects of psyllium as an adjunct to diet therapy in the treatment of hypercholesterolemia. The American Journal of Clinical Nutrition. 2000;71(6):1433-1438. doi:10.1093/ajcn/71.6.1433
Groenendijk I, den Boeft L, van Loon LJC, de Groot LCPGM. High versus low dietary protein intake and bone health in older adults: A systematic review and meta-analysis. Computational and Structural Biotechnology Journal. 2019;17:1101-1112. doi:10.1016/j.csbj.2019.07.005
