More and more people are combining different diets without medical supervision. Scientists warn that the practice can create eating disorders and lead to nutritional deficiencies.
As the new year approaches, many people turn to restrictive eating plans in an attempt to improve their health or lose weight. But a new one published in the Journal of Gastroenterology and Hepatology Open warns that combination of several diets At the same time, a practice known as “stacking diets” can pose serious risks to physical and mental well-being.
The research, led by scientists at Swinburne University of Technology, argues that while individual diets can be beneficial, combining multiple dietary approaches can significantly increase the likelihood of nutritional deficiencies and eating disorders.
“Individually, many diets have their merits,” said Dr Caroline Tuck, senior lecturer in dietetics at Swinburne and lead author of the study. “But combining them can amplify risks such as nutritional insufficiencies.”
Overlapping diets generally occur when people adopt several restrictions simultaneously, such as vegetarianism, gluten-free diet, low-fat diet, low-FODMAP diet, without professional guidance or a clear medical need. According to researchers, this approach is particularly common among people dealing with gastrointestinal illnesses, but is increasingly seen in the general population, influenced by diet culture and social media trends.
The study highlights that some medical conditions, including inflammatory bowel disease (IBD) and celiac disease, may require specific dietary interventions. In these cases, and under clinical supervision, following one or even several eating plans may be appropriate. However, researchers emphasize that unsupervised dietary restriction may worsen symptoms and reduce overall diet quality.
People with gastrointestinal disorders are already at increased risk of nutritional deficiencies. IBD can increase the body’s energy and protein needs, while celiac disease affects nutrient absorption. Adding unnecessary restrictions can intensify existing nutritional challenges, potentially leading to fatigue, weakened immunity and mental health problems.
In the long term, the study warns, excessive dietary restriction can contribute to chronic health problems, such as heart disease, type 2 diabetes, osteoporosis and obesity. It can also increase the risk of eating disorders, including anorexia and orthorexia, says .
“Overlapping diets, especially when self-imposed and not carried out in collaboration with a nutritionist, probably represents a significant risk factor for the development of eating disorders,” write the authors, who recommend routine screening for eating disorders in people who adopt multiple restrictive diets.
