After a few weeks of Christmas indulgence, many of us tend to use January as a time for making drastic changes to our diets.
But research has emerged which suggests that taking a multi-pronged approach to food-based resolutions can actually end up being bad news for our health.
The scientists have cautioned against a wellness trend dubbed ‘diet stacking’ in which people following multiple dietary approaches at the same time—for example, combining vegetarian, gluten-free, low-fat, low-FODMAP or “clean eating” plans—often without professional guidance.
While each diet on its own may have evidence-based benefits, the team warns that layering them together can lead to increased physical, nutritional and psychological risks.
The research—led by Swinburne dietetics expert Caroline Tuck in collaboration with Monash University’s Sarah Melton—found that people often accumulate restrictive diets in pursuit of symptom relief, weight loss or gut health without stopping approaches that are not working, or even assessing whether they are appropriate in the first place.
“In some cases, the use of multiple diets is necessary and evidence-based,” Tuck said. “But in other cases, people may accumulate diet strategies by layering them with additional restrictions such as gluten-free, low-fat, or ‘clean eating’ without considering whether they’re right for them or discontinuing diets that are ineffective.”
The team note that the risks of diet stacking extend well beyond short-term fatigue. Over time, excessive restriction can contribute to nutrient deficiencies and raise the likelihood of chronic health conditions: including heart disease, type 2 diabetes, obesity, osteoporosis, weakened immunity, poor mental health and persistent exhaustion.
One major concern highlighted by the researchers is that diet stacking can sometimes replace—rather than complement—medical treatment.
In gastrointestinal conditions especially, patients may become overly focused on food as the primary solution, leading to under-treatment of the underlying condition and delayed recovery. Health professionals are then faced with the challenge of rebalancing expectations and addressing both nutritional and psychological risks.
The psychological impact is also troubling. People with gastrointestinal conditions already face a higher risk of disordered eating, and the research suggests diet stacking may intensify that vulnerability.
Certain factors may further increase the risk, including body image concerns, perfectionism, psychological distress, social pressure and more severe gut symptoms.
Researchers also point to loneliness and social isolation as overlooked consequences, as strict diets can make shared meals, celebrations and eating out stressful or even inaccessible.
From a nutritional standpoint, stacking diets can also sharply reduce food variety, which is essential for meeting macro- and micronutrient needs.
This risk is also amplified for people already managing gastrointestinal disorders, where symptoms may impair digestion, absorption and appetite. Combining therapeutic diets without careful planning can lead to deficiencies in calcium, fiber, folate, iron, key vitamins and protein.
Tuck pointed to the example of someone who is vegetarian and begins a low-FODMAP diet to manage gut symptoms. Many common vegetarian protein sources are high in FODMAPs, meaning protein intake can quickly become inadequate without expert guidance.
Other diets—such as short-term exclusion plans for Crohn’s disease—are not nutritionally complete if followed long-term and require supplementation to avoid undernutrition.
Even lifelong therapeutic diets, such as gluten-free eating for coeliac disease, require careful management. Gluten-free grains tend to be lower in fiber and higher in fat and sodium, which can affect satiety, appetite regulation and long-term cardiometabolic health if not balanced appropriately.
Tuck said the takeaway is not to abandon dietary changes altogether, but to approach them thoughtfully.
Working with an Accredited Practicing Dietitian can help ensure that dietary strategies are evidence-based, nutritionally adequate and sustainable.
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Reference
Melton, S. L., Knowles, S. R., Gwee, K.-A., Gibson, P. R., Tuck, C. J., & Day, A. S. (2025). Diet Stacking – An Expanding Challenge for Gastroenterologists and Dietitians in Managing Chronic Gastrointestinal Disorders. JGH Open, 9(12). https://doi.org/10.1002/jgh3.70314