More research is needed to understand which patients are best suited for the diet; “however, given the associated rapid weight loss, the use of [very low-energy diets] 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,” first author Megan Gow, PhD, of Children’s Hospital Westmead Clinical School, The University of Sydney, Westmead, Australia, said in a press statement.
The study will be presented in May at the upcoming European Congress on Obesity, in Venice, Italy.
While very low-calorie diets have been shown to promote rapid weight loss in adolescents, research is lacking on general side effects and acceptability of the regimens. Data is also lacking on important issues including the diet’s effect on growth, heart health, and psychological wellbeing.
To investigate, Dr. Gow and colleagues conducted a subanalysis of the 52-week Fast Track to Health study evaluating the acceptability of different dietary plans for adolescents with obesity.
The analysis included 141 adolescents between the ages of 13 and 17 years with moderate to severe obesity (average body mass index, 35 kg/m2) and at least one obesity-related complication, such as high blood pressure or insulin resistance.
The participants were placed on a nutritionally balanced very low-energy diet consisting of 800 calories per day.
The diet involved one of two regimens — either four Optifast-formulated meal replacement products per day, including shakes, soups, bars, and/or dessert, along with low carbohydrate vegetables, such as broccoli, celery, capsicum, mushrooms, and tomatoes, with one teaspoon of vegetable oil, or a regimen 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.
Participants, about half of whom were women, also received dietitian support at least weekly.
After 4 weeks, most of the adolescents, ie, 134 of the 141, with an average age of 14.9 years, completed the diet, with an average weight loss of 5.5 kg or 12 pounds (P < .001).
Most patients (95%) experienced at least one side effect, and 70% reported at least 3 of the side effects, with the most common side effects including hunger, fatigue, headache, irritability, loose stools, constipation, nausea, and a lack of concentration.
Viral infections occurred in seven participants.
While most side effects occurred at the end of week 1, the development of side effects earlier, at day 3-4, was associated with higher levels of weight loss at the 4-week cut-off, which the authors noted could suggest a greater adherence to the diet at that stage.
One adverse event occurred, consisting of a single fainting episode determined to be potentially related to the dietary intervention.
In surveys, the adolescents gave the intervention an acceptability rating of 61 on a scale of 100, the score was 53 of 100 in terms of being “enjoyable to follow.”
The most-liked aspects of the intervention were losing weight (described by 34% of participants) and the prescriptive structure (listed by 28% of participants).
The least-liked aspects included the diet’s restrictive nature, described by 45% of participants, and the taste of meal replacement products, listed by 20% of participants.