September 25, 2014

There’s an interesting ad on TV at present for weight loss using meal replacements. What’s interesting is not that these products are being advertised, but that they are using the word ‘ketosis’ as a selling point. The question is whether or not ketosis is essential for weight loss.

Most people would ask: What is ketosis?

In his excellent book Keto Clarity, author Jimmy Moore defines ketosis as “a metabolic state that happens when you consume a very low-carb, moderate protein, high fat diet that causes your body to switch from using glucose as its primary source of fuel to running on ketones. Ketones themselves are produced when the body burns fat, and they’re primarily used as an alternative fuel source when glucose isn’t available.”

Put simply, for the body to be in ketosis, glucose (from sugars and carbohydrates) must be low enough that fat is burned for fuel. You become a fat-burner rather than a sugar-burner.

The ‘very low-carbohydrate’ intake to induce ketosis will be different for everyone. Reasons for these differences may in part be genetic, but are primarily due to the amount of metabolic damage that has been done over the course of a lifetime. There will be some trial and error to determine whether your carb intake is sufficiently low to induce ketosis, and you’ll only know for sure if you regularly test for ketone bodies.

Some people will need to have a carbohydrate intake as low as 15g per day to be in ketosis; those are the people who may have a long history of obesity and/or a long history of over-eating highly refined processed foods. People who have never been overweight and/or always eat a diet of whole, unprocessed foods are very likely to be able to manage a much higher carbohydrate intake, perhaps 150g daily, to be in ketosis.

It’s clear that one size doesn’t fit all, so flexibility within the weight loss strategy is essential.

Let’s compare the meal replacement products in the TV ad – which states that you’ll be in ketosis if you have three meal replacements per day – with eating real, whole foods where you know exactly what the ingredients of the meal are and where they came from.

Meal replacementsCaloriesProtein (g)Fat (g)Carbohydrate (g)
Caramel shake20717.54.522.5
Chicken flavour soup17318.32.717
Cappuccino flavour bar22618.36.920.4
Daily total60654.114.159.9


Real foodCaloriesProtein (g)Fat (g)Carbohydrate (g)
2 eggs, butter, mushrooms, spinach26218.419.11.3
Green salad, chicken, olive oil32632.120.32.7
Porterhouse steak, béarnaise sauce, broccoli, green beans, zucchini32225.718.810.4
2 snacks daily30025314
Daily total1210101.261.228.4


It’s important to note that dietitians recommend going no lower than 1200 calories per day. Too few calories and too little protein leads to muscle wastage, so the weight on the scales might look good but in the long term slows metabolism further.

Eating too little, of course, also leads to hunger, cravings and dissatisfaction with the diet, so for many people between-meal snacks are essential for preventing hunger and helping them stay on track.

Talk to nearly anyone who has lost weight successfully and you’ll find that the true indicator of success is whether they can continue with their new habits to keep the weight off long term. Sustainable weight loss is the goal.

Ketosis? Who knows? As stated earlier, the total daily carbohydrate intake will differ according to the individual’s specific needs. Testing is the only way you’ll know for sure, but for most people the goal is not to be in ketosis but to simply lose weight and enjoy the food they’re eating.

You can see from the sample suggestions here that preparing meals from real food can be quick and easy. We know what we prefer. How about you?