Hi Tilly,
The norm for weight loss is use a calorie calculator like this: http://www.freedieting.com/tools/calorie_calculator.htm - and then consumer either 500 calories a day less, or for rapid weight loss go 1000 a day less than what you body needs per day.
I’ve just read the article you linked to and it says the diet is 800 calories per day (600 from shakes and 200 from green veg). My daily requirement of calories is 2300 so to only 800 is a daily deficit of 1500 which is too much is my opinion.
With Huel is a easy to know exactly how many calories you consumer, you simply weight the powder then calculate how many calories are in it. However, we have designed it to provide all the macro and micro nutrients at 2000 calories and above.