Very low-calorie diets are “safe” for severely obese adolescents under guidance, study suggests

18 Mar 2024 --- An Australian study finds that short-term, very low-calorie diets are a “safe” method of weight loss for teenagers with moderate to severe obesity. With supervision, the approach is considered viable for individuals who do not respond to conventional diet and exercise programs and may be used instead of bariatric surgery. 

Very low-energy diets (VLED) typically involve taking in ≤ 800 calories per day and include meal replacements (bars and shakes) to ensure all essential nutrient requirements are met.

Despite experiencing side effects, many adolescent participants consider a very low-calorie diet to be an “acceptable” way to lose weight after completing the study.

“More research is required to determine who would be most suited to a VLED,” says Dr. Megan Gow, of Children’s Hospital Westmead Clinical School, The University of Sydney, Westmead, Australia.

“However, given the associated rapid weight loss, their use should be emphasized in clinical practice guidelines for the treatment of severe obesity and obesity-related complications in adolescents, especially before pharmacological or surgical intervention.”

“Adolescents who are seeking treatment for their obesity should see their family doctor to discuss treatment options.”

There is limited data on the impact of VLEDs on the growth, heart health and psychological well-being of young people.The research will be presented at the European Congress on Obesity (ECO 2024), which will be held in Venice, Italy, May 12–15. 

Addressing limited data
Although studies have shown that VLEDs can lead to rapid weight loss in young people, there is very little data on general side effects — such as headache, fatigue, muscle cramps, constipation — and the acceptability of VLEDs in young people. 

There is also limited data on the impact of VLEDs on the growth, heart health and psychological well-being of young people, and, as a result, some physicians have been reluctant to use them in this age group.

Dr. Gow and colleagues carried out a sub-analysis of data from Fast Track to Health, a 52-week study into the acceptability of different eating plans for adolescents with obesity.

Data from the first four weeks of Fast Track to Health, during which participants followed a nutritionally balanced VLED to kick-start their weight loss, was included in the sub-analysis.

The study involved 141 (70 female) participants aged 13–17 years with obesity and at least one obesity-related complication, such as high blood pressure, insulin resistance or dyslipidemia.

The participants consumed 800 calories a day from four Optifast formulated meal replacement products per day (shakes, soups, bars and/or desserts), with low carbohydrate vegetables (for example, broccoli, celery, capsicum, mushrooms and tomatoes) and one teaspoon of vegetable oil.

Another meal plan option consisted of three Optifast formulated meal replacements and one meal consisting of 100−150 g lean, cooked meat, low carbohydrate vegetables and one teaspoon of vegetable oil. 

Side effects observed after one week
A dietician of the study offered support at least weekly. Participants’ weight was recorded at baseline and week four and side-effects were recorded on the third and fourth day and after one, two, three and four weeks. 

The adolescents also filled in a survey about how acceptable they found the VLED, including what they liked most and least.

Nearly all adolescents in the study (134 out of 141) completed the VLED program (average age of 14.9 years, 50% male), despite side effects being very common. The average weight loss was 5.5 kg (12 lb).

VLED intervention is considered “acceptable” for many adolescents with moderate to severe obesity, despite side-effects.Nearly all (95%) experienced at least one side-effect during the VLED while most (70%) experienced at least three side-effects. The most common factors were hunger, fatigue, headache, irritability, loose stools, constipation, nausea and lack of concentration. 

Seven of the participants experienced viral infections.

Side effects were most common at the end of week one. Experiencing more side effects on the third and fourth days was associated with more significant weight loss at the end of the four weeks, “possibly indicating increased adherence to the VLED.”

Half of subjects rate approach “enjoyable”
The adolescent participants rated the intervention as 61/100 for “easy to follow” (easy = 100, difficult = 0) and 53/100 for “enjoyable to follow” (enjoyable = 100, not enjoyable = 0 points).

The most-liked aspects of the VLED intervention were “losing weight” (34% of participants) and the “prescriptive structure” of the diet (28% of participants). Meanwhile, “restrictive nature” (45% of participants) and “taste of meal replacement products” (20% of participants) were liked least.

The researchers conclude that a health professional-monitored VLED can be implemented “safely” in the short-term and is “acceptable” for many adolescents with moderate to severe obesity, despite side-effects.

In previous research into effective weight management, scientists identified that high-fat diets stimulate overeating and lead to obesity. Another study found plant cell-derived saffron may aid in “unlocking weight loss potential.”

Edited by Benjamin Ferrer