Is a keto diet a good way to lose weight?
The low-carb, high-fat ketogenic diet has been promoted online and in the media as a weight-loss tool and seemingly all-round magical healer. Yet it was for children with epilepsy.
There鈥檚 no shortage of celebrity and influencer fans. Previously, Jersey Shore star Vinny Guadagnino, Kourtney Kardashian and Halle Berry have all spoken about following the keto diet. But even the health and wellness influencers may not be qualified nutritionists or dieticians. 鈥淣utritional advice is highly unregulated, particularly online鈥, says dietitian Sophie Medlin.
As of now, #keto has around 27 million tags on Instagram.
When you鈥檙e following a keto diet you aim to be in a state of 鈥榢etosis鈥. We ask the experts what ketosis is, if it鈥檚 worth the effort and if it鈥檚 safe.
What do you eat on a keto diet?
Your body uses whichever energy source is most readily available. This is normally glucose (sugar) converted from carbohydrates. If you drastically limit your carbohydrate consumption and replace it with fat, your body is eventually forced to use fat from food or your stores as energy instead. This process is called 鈥榢etosis鈥. 鈥淚t is essentially the Atkins diet repackaged and renamed鈥, says Medlin.
鈥淢ost people calling their diet 鈥榢eto鈥 are simply following a low or very low-carbohydrate diet鈥, she continues. The degree to which you need to restrict carbohydrates to be in ketosis 鈥渧aries from person to person鈥, she adds. In a clinical or therapeutic setting, such as for children with epilepsy, the diet is designed specifically for the individual and support and monitoring are provided.
Low-carb, high-fat ingredients include avocados, meat, fish, eggs, cheese, cream, oil, butter, nuts and seeds. But not all ingredients need to be high in fat 鈥 leafy greens and berries are often included, for example. You avoid, or at least heavily restrict, wheat and other grains, potatoes, corn, pulses, beans, milk, most fruit and sugar.
To induce ketosis, a maximum of 20鈥50g carbohydrates can be consumed daily for someone eating 2,000 calories a day, according to on the ketogenic diet. To put this into perspective, a banana contains about 20g and a plain bagel 44g. Protein is also usually kept to a moderate amount, as it can encourage the production of glucose and interrupt ketosis.
The keto diet has few rules on which high-fat foods to eat, and 鈥榙irty keto鈥 can consist of bacon and sausages fried in butter, as this technically meets the criteria. Medlin says the should always roughly apply, even if you limit carbohydrates and regardless of what diet you're following.
Will a keto diet help you lose weight?
Research has shown a ketogenic diet can induce rapid weight loss, partly from water loss but also some fat loss. However, the 鈥渨eight loss effect becomes similar to other dietary approaches after one year鈥, according to a of low-carb diets.
Taking in less energy than you burn will lead to weight loss. The reports that on average we get almost 50 percent of our energy from carbs. 鈥淐utting this by at least half is likely to reduce total calorie intake, even if it鈥檚 replaced with fats鈥, says Medlin. On the other hand, if you eat more calories from fat than your body needs it will still be stored as fat.
The 鈥榚at like me to look like me鈥 ideology is flawed. 鈥淲e all have different genetics and lifestyles, which means we can鈥檛 all look the same鈥, says Medlin. the best weight-loss diet is the one you can stick to for long enough to reduce excess body fat.
with the keto diet is low. Medlin cites restricting a whole food group, symptoms known as 鈥榢eto flu鈥 (including headaches, nausea, constipation, tiredness and difficulty sleeping) which can kick in after two to seven days, and the higher-than-average cost of the diet as potential reasons why people might struggle to stick to it.
鈥淭he keto diet is used for certain therapeutic situations and isn鈥檛 meant for the mainstream weight-loss market鈥, says dietitian Priya Tew. 鈥淐arbohydrates have an important role in our diets and whilst reducing them may aid weight loss it is not sustainable to reduce them to a very low level.鈥
Is a keto diet safe?
鈥淢any of the trials investigating ketogenic diets only follow participants for around six months up to one year at the most鈥, says nutritionist Emma Thornton, 鈥渢herefore, the longer term effects鈥 aren鈥檛 well understood.鈥
Medlin says the health risks also depend on the types of food eaten. Eating an unhealthy diet containing lots of saturated fat may such as heart disease and stroke.
Foods containing carbohydrates are often also high in fibre, which is important for a healthy gut microbiome and keeping you fuller for longer. Medlin advises anyone on a low-carb diet to ensure they eat enough fibre-rich foods from leafy greens, broccoli, cauliflower, flax seeds, nuts, coconut and avocado.
The keto diet limits starchy vegetables such as carrots, sweet potatoes, parsnips, pumpkin and squash and eliminates many fruits. This might restrict the amount and variety of nutrients, vitamins and phytochemicals (plant power) you get from your food, especially if you remove them rather than replace them.
People who restrict their carbohydrates and increase fatty foods may develop 鈥榢eto flu鈥. There is very little medical research on this, but there are thousands of personal testimonies. Though it sounds unpleasant, it isn鈥檛 necessarily unsafe and many reports indicate the discomfort subsides. It is also not clear whether it only occurs on the keto diet or can be caused by other restrictive diets.
The keto diet might not be for everyone
If you take any medication or have any medical issues, consult a doctor or dietitian before starting a keto diet. For some people, a keto diet may cause harm, even with careful monitoring.
Alternatives ways to lose weight
鈥淚 recommend checking your portions sizes are sensible, with potentially a small decrease in these and an increase in your vegetable intake鈥, says Priya Tew. She does not recommend reducing your carbohydrate intake to less than a quarter of your diet.
鈥淪mall steps make a big difference鈥, says Emma Thornton. She suggests cooking from scratch at home and expanding your knowledge of fresh ingredients is a good starting point. She also says other higher-fat and lower-carb diets, such as the popular Mediterranean-style diet, can be healthy as long as plenty of fish, nuts, seeds, other foods rich in healthy fats and vegetables are on the menu.
A key way to address weight-loss is to look at 鈥渨hy you eat rather than what you eat鈥, according to Medlin. Stress, poor sleep and choosing unrealistic diets have been identified as some of the main reasons people discontinue their weight-loss diet. An suggests the most effective strategy for long-term weight-loss and heart health is a healthy diet pattern that's compatible with your food preferences and lifestyle. 鈥淚t鈥檚 really important not to beat yourself up over having some birthday cake or foods you love once in a while鈥, concludes Medlin.
Originally published September 2019
