Diane Munns is a Practising Dietitian and Nutritionist with 30 years’ experience. She is also an Accredited Practising Dietitian for SuperFastDiet.com, and the Director of Northern Beaches Diabetes and Weight Management. Both keto and intermittent fasting have become very popular weight loss regimes – or ‘dietary lifestyles’ as they are more often referred to. But, which one is more effective for weight loss? Firstly, let’s break down the two.
What is keto?
Keto is short for ‘ketogenic diet’, and dieters need to keep their carb level anywhere below 50g per day (with strict dieters containing carbs to around 10 – 20g of carbs). Therefore, 10 per cent or less of your calorie intake comes from carbs. Approximately 20-30 per cent of your calories come from protein and about 60-70 per cent from fats. So, it’s a low-carb, moderate protein, high fat diet.
Keto can be quite challenging, and it is debatable as to whether being in nutritional ketosis full-time doesn’t come without some adverse health outcomes for some individuals.
What is intermittent fasting?
Intermittent fasting often refers to a ‘time restricted eating window’. It’s also occasionally called ‘interval eating’ or ‘part-time dieting’ because of the intermittent nature of the dietary lifestyle. There are several methods to choose from depending on a person’s individual situation, which makes this dietary lifestyle very flexible. There’s the 5:2, the 16:8, and other longer fasts such as a 24-hour fast, whereby you eat dinner and then don’t eat until dinner again the next evening.
You can also mix the different regimes up e.g 1 x 500-calorie day on a Monday and 2 x 16:8 days that week. What’s appealing to many people is that there are no foods or drinks that are ‘off the menu.’ All up, this equates to a ‘no fail’ dietary approach – or basically, a dietary lifestyle that can’t be broken (because it’s designed to be).
What are the benefits and potential pitfalls of keto?
Due to its very restrictive carbohydrate level, the keto diet can be psychologically and socially difficult for some people to adhere to. However, once ‘nutritional ketosis’ is achieved, clients report being very happy and generally not feeling hungry at all. They really like the food that’s on the menu and the fact the diet is based on real whole foods. And not only do they get great results in terms of weight loss, they often see other benefits like reversal diabetes.
Some potential pitfalls are that a ketogenic diet can be deficient in some nutrients if it’s not planned properly, particularly fibre, and especially some vitamins and minerals (like vitamin C and B group vitamins, vitamin D, and calcium) since ‘strict keto’ practically eliminates fruit and milk.
What are the benefits and potential pitfalls of intermittent fasting?
Intermittent fasting is fairly flexible, and the client feels they are in control of the regime they choose. It’s kind of like being your own boss. You get to choose when your fasting days and feasting days are. It’s easy as in it can be part-time, and social events can be enjoyed without guilt. Some people complain of hunger initially but once they get used to it, this isn’t so much of a problem.
Some of the benefits of intermittent fasting include better blood sugar control, weight loss, reduction in age-related disease markers, and according to early animal study, longevity, too. In short, it’s a doable dietary lifestyle regime long-term.
So, which one is better for weight loss?
The bottom line is that either of these diets will effectively help you lose weight. In the short term, if the diet chosen isn’t ‘perfectly’ balanced, there’s probably no harm done. However, in the long-term, the key is to make sure these diets are planned properly so you get all the nutrients you require for your individual health profile and so you can sustain the dietary regime long-term.
I don’t know that anyone really needs to do keto full-time or that anyone would actually be able to manage a diet like this 100 per cent of the time. Intermittent fasting on the other hand, provides all the health benefits that keto does, in terms of reducing blood glucose levels and weight loss (without the harsh restriction of carbs). Dietitians have many tools in their tool basket to assist people with their weight loss journeys and some are more easily managed than others.
Ultimately, there is no one-size-fits all approach, but in my opinion and experience, intermittent fasting is definitely a more manageable dietary lifestyle long-term.
Can you combine keto with intermittent fasting?
Yes, you can, but why be so strict? Instead, why not liberalise the keto constraints and go low-carb, healthy-fat (LCHF) combined with intermittent fasting? That way, you can have the best of both worlds. LCHF is the base diet that I teach to many of my clients, and then I encourage them to throw in the intermittent fasting regimes they choose to use. This is a really supercharged way to achieve optimum weight loss. Having time off from either (or both!) is okay, too.
To explain a little more about the difference: LCHF contains carbs from anywhere between 50-100g per day, and even up to 150g on the more liberal end. In my experience, people who are unaware of their diets can be consuming more than 400g of carbs a day. This can lead to an increase in insulin resistance (IR). IR is the precursor to weight gain, diabetes, obesity, and many other metabolic conditions.
Learning how to keep the carbs controlled and satiate yourself with a moderate amount of protein and increased amounts of healthy fats, is really the base for long-term success. Feeling satisfied by consuming an increased amount of fat in the diet is such a relief for everyone who has tried numerous fad diets in the past. No one wants to feel hungry while trying to lose weight. Adding intermittent fasting along with the LCHF approach would be the next step I would recommend.
So, while I don’t necessarily advocate keto (but will support someone already doing it), I do advocate LCHF and intermittent fasting, especially as a combined approach.The bottom line
No matter what diet or dietary lifestyle you choose, you need to make sure that long-term it is nutritionally balanced for your individual medical and health profile. I’d suggest that you work in conjunction with your GP and Accredited Practising Dietitian to get the best results for you.
I do have one word of caution: some medications may need the dose to be altered when you lose weight. For example, thyroid meds, diabetes meds, insulin requirements, blood pressure meds, neurological and psychiatric meds, just to name a few. Make sure your doctors know what dietary approach you are considering, and always see your GP or health care professional before embarking upon a new dietary or exercise regime.