Surgical intervention for weight loss (bariatric surgery) can result in substantial weight loss that is sustained over the long-term when combined with education, ongoing monitoring and patient support.

Your surgeon may have suggested that you use a Very Low Calorie Diet (VLCD) also known as Very Low Energy Diet (VLED) for a period of time prior to your planned surgery. By following the VLED weight loss program you restrict your daily kilojoule intake and carbohydrate intake to a level lower that your body requires. This results in weight loss as your body metabolises your excess body fat for the energy it needs in a metabolic process called ketosisTreatment with the VLED Program before bariatric surgery has been shown to result in significant weight loss and reduction in liver size (Pekkarinen et al 1997). Weekly weight losses average approximately 2.0kg in the first 4-6 weeks if complied with. Moreover it is important for safety during surgery as if the liver is large and inflamed it becomes an obstacle and therefore a hazard for the surgeon. Various studies have shown a significant reduction in liver volume following a 4 week VLCD pre-bariatric surgery (Fris 2004; Lewis et al 2006). 

There are various ketogenic diets on the market. All involve meal replacements and usually this is with a shake or a bar, ie shake/bar for breakfast and lunch and protein and veggies/salad for evening meal, supplemented with fibre, plenty of water and oodles of willpower.

Without a doubt the product works if you can strictly adhere to the programme but they can be difficult to stick with over a long period of time. It can become monotonous and we like to taste and chew food so shakes lose their pizazz after a while. I have come up with a few tips that have helped my patients remain steadfast to the VLED because at the end of the day if you want a surgical weight loss procedure, the VLED is not negotiable and more importantly your safety is not negotiable.



If you are the person who likes to chew in the morning then the bar is good with your coffee or tea but if you are the person who skips breakfast (don’t do it) or has breakfast on the run then the shake is a great option. Make sure you add benefibre (fibre supplement) to your shake or your water bottle.

Morning Tea

Here you can have your tea or coffee as usual but no food, but top up on your water intake.

Lunch Time

Have your lunch a little earlier than usual. The VLED will prescribe a meal replacement shake or bar here also and most VLED’s offer a selection of free veggies/salad greens that can be eaten in any quantities at any time during the programme. I suggest making up a large salad from the free salad, with a little vinaigrette dressing or a little olive oil. Have this at lunch instead of the shake/bar as I have plans for the bar/shake later. If you are still hungry it is a good idea to add a small quantity of protein to your salad, for example ½ tin of tuna or a sliced boiled egg occasionally or small amount of grated cheese. These will certainly jazz up the salad and add some variety for you but more importantly, will not hinder the process of ketosis so necessary for shrinking the liver.

Afternoon Tea

Very often the afternoon is when people feel tired and will reach for the first thing they see to eat. Have the shake or the bar that was planned for lunch at this time and this will definitely see you through to dinner. There are plenty of flavours, so plenty to keep the tastebuds stimulated.


No great change to dinner, so protein quantity as per you VLED and veggies or salad as prescribed by the VLED. It is better to have dinner a little earlier and remember earlier to bed also so that there is no temptation to snack in front of the TV.

Very Important

8 glasses of water at the very minimum

Fibre supplement to prevent constipation

Sugar free mints or chewing gum for the ketosis breath

Eat slowly and mindfully

Incorporate daily exercise into your routine (every little helps)

NB: Carbohydrate restriction is the key to ketosis and VLED weight loss. It is important then to remember to follow the VLED program as prescribed to ensure the best weight loss results. Consuming additional carbohydrates will prevent ketosis and therefore stop weight loss.


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