Very Low Calorie Diets, or VLCDs are often used (under medical supervision) to assist people who are obese to lose large amounts of weight in a relatively short period of time. Defined as a diet of less than 800 calories per day, VLCDs are generally meal replacement products that are reconstituted to make a liquid shake. People who are on a VLCD lose weight due to their significantly restricted calorie intake.
Although significant weight change can be achieved with VLCDs, there are some risks associated with these types of approaches, and it is definitely not for everyone! Minor side effects include fatigue, constipation, nausea and diarrhoea, but more serious reported side effects include formation of gallstones.
Previous research has focussed on the association between VLCDs and gallstones identified using ultrasound. For this study, researchers in Sweden sought to understand the incidence of gallstones that required hospital care or surgery involving removal of the gallbladder in relation to use of VLCDs.
The study was conducted by analysing customers of a commercial weight loss clinic in Sweden. 6,640 participants chose whether to participate in a VLCD or low-calorie diet approach.
The VLCD was a liquid-based formula diet of 4 x 125 calorie sachets (for a total of 500 calories) per day. Each sachet contained 13g protein, 15g carbohydrates, 2g fat and 3g fibre. For an initial 6-10 week period, participants consumed the sachets only; after that time, normal food was reintroduced.
Participants who elected the low-calorie diet ate 1,200 -1,500 calories per day; this was made up of two calorie-restricted normal food meals and two formula diet meal replacement sachets (each 125 calories). The meals included restricted portion sizes and were high in protein, low in overall energy density, and also had a low glycaemic index.
After three months, both groups continued with a 9-month maintenance program, including exercise, increased movement and use of a pedometer, dietary advice, self monitoring and behavioural changes.
Prior to commencing the weight loss program, participants were approximately 46 years of age, with a body mass index of 33.4kg. 83 per cent of participants were female. For analysis, participants from each group were matched based on age, sex, BMI, waist circumference, and history of previous gallstones. This left 3,320 participants in each group.
82 per cent of the VLCD group and 78 per cent of the low calorie diet group completed the full 1 year program. Their weight loss results are outlined below:
After 3 months:
• The VLCD group had lost on average 12.7 kg
• The low calorie diet group had lost 7.9 kg
After 12 months:
• The VLCD group had lost 11.1 kg
• The low calorie diet group had lost 8.1 kg
During the follow up analysis:
• 48 gallstones requiring hospitalisation occurred in the VLCD group compared with
• 14 gallstones requiring hospitalisation occurred in the low calorie diet group; and
• 29 cases of gallbladder removal occurred in the VLCD group compared with
• 9 cases of gallbladder removal occurred in the low calorie diet group.
This large-scale study indicates that there many be a relationship between the use of VLCDs and gallstone disease. The authors found that although the overall risk of gallstones or gallbladder removal was low, it was approximately three times higher in the VLCD group than the low calorie diet group.
Although exactly what causes the formation of gallstones is not yet clear, it is possible that the link with VLCDs is a result of inadequate fat intake in the diet, or the quick weight loss associated with these products.
Previous research has connected VLCDs with formation of gallstones. Although working with smaller sample sizes and more limited study designs, those studies indicated that VLCDs with between 12 and 30g of fat per day, were associated with a lower risk of gallstone formation. (The VLCD product used in this study contained 7g per day of fat.)
This study raises the question of whether the additional weight lost through VLCDs justifies the increased risk of gallstones or gallbladder surgery compared with low calorie diets. Ultimately, this may come down to the client’s medical history, risk factors and personal preference. It may be helpful to supplement VLCDs with omega-3 fatty acids and/or ursodeoxycholic acid (a medication used to dissolve gallstones). These findings reinforce the importance of medical supervision whilst using VLCDs for weight loss.
Reference: Johansson, K., Sundström, J., Marcus, C., Hemmingsson, E., & Neovius, M. (2014). Risk of symptomatic gallstones and cholecystectomy after a very-low-calorie diet or low-calorie diet in a commercial weight loss program: 1-year matched cohort study. International Journal of Obesity, 38(2), 279–84.
Have your clients incorporated VLCDs into their weight loss efforts? Did they experience any side effects? Share your experiences in the comments below.