According to a new study published in Frontiers in Nutrition, swapping out meat, eggs, and dairy for greens and beans may help reduce inflammation and support sustainable weight loss.
What Did the Study Find?
In a randomised cross-over trial, researchers studied 62 overweight adults who were randomly assigned to a Mediterranean diet or a low-fat vegan diet for 16 weeks. After a four-week cleansing period, each group followed the alternate diet for another 16 weeks, which means they acted as their own controls.
Researchers measured the participants’ dietary acid load, which is calculated using two scores: potential renal acid load (PRAL) and net endogenous acid production (NEAP). The former estimates how much acid the kidneys need to remove, and the latter estimates the total amount of acid your body produces, including from digestion and metabolism.
If that all sounds a bit complex, the main thing to know here is that increased dietary acid load is linked to chronic inflammation, which can disrupt metabolism and lead to increased body weight. So, essentially, the researchers were looking for lower dietary acid load scores.
The Mediterranean diet followed the PREDIMED protocol, which includes fruits, vegetables, legumes (eg, lentils, chickpeas, peas, beans or soy), nuts or seeds, fish or shellfish, and prioritises lean white meats over red meats. Participants were also asked to consume 50g of extra-virgin olive oil every day. Meanwhile, the vegan diet included vegetables, grains, fruits, and legumes.
Following a statistical analysis, the researchers found that both PRAL and NEAP scores decreased significantly on the vegan diet, with no significant change on the Mediterranean diet. This reduction in dietary acid load was associated with weight loss, which the researchers say remained significant even after they accounted for the higher calorie intake on the Mediterranean diet. Body weight was reduced by an average of six kilograms on the vegan diet, compared with no change on the Mediterranean diet.
What Does This Mean for Us?
Animal products like meat, fish, eggs, and cheese do cause the body to produce more acid, and the researchers say that the vegan diet’s alkalising effect, which increases the body’s pH level to make it less acidic, may be what helps promote weight loss.
Top alkalising foods include:
- Leafy greens
- Broccoli, beets
- Asparagus
- Garlic
- Carrots
- Cabbage
- Berries
- Apples
- Cherries
- Apricots
- Cantaloupe
- Lentils
- Chickpeas
- Peas
- Beans
- Soy
- Quinoa
- Millet
These results highlight the benefits of a plant-based diet for reducing inflammation. Because plant-based diets are more alkaline, the researchers say they are generally associated with weight loss, improved insulin sensitivity, and lower blood pressure.
That’s not to say you need to go entirely plant-based to reap those benefits, but the findings suggest that if your aim is to (sustainably) lose weight, a wholly plant-based approach might be optimum, seeing as the Mediterranean diet – which is also high in plants – didn’t produce the same results.
It’s important to remember that the study looked at overweight individuals, so while it suggests a temporary plant-based diet could be a good way to kickstart a sustainable weight loss journey, it’s probably not for you if you’re already quite active. We need ample fats and carbs to fuel regular training, and while a vegan diet can absolutely still work, it likely wouldn’t in conjunction with a low-fat approach.
However, when weight loss drugs (which can be a valid and helpful option for some people) are increasingly being promoted by unqualified sources as quick-fix solutions over nutrition and exercise, studies like this highlight the potential powers of nutritional interventions first.
The Bottom Line
Although the study had a rigorous design, it was relatively small and relied on self-reported dietary data from participants. Also, while the researchers say their statistical analysis accounts for the extra energy intake on the Mediterranean diet, some might argue that it could still have impacted outcomes.
With that in mind, more research is needed to confirm the results. However, for now, the study highlights the potentially powerful health benefits of including more plants in your diet – and how a temporary vegan diet could help you kickstart a sustainable weight loss strategy.
Hannah Bradfield is a Senior Nutrition Writer across Women’s Health UK and Men’s Health UK. An NCTJ-accredited journalist, Hannah graduated from Loughborough University with a BA in English and Sport Science and an MA in Media and Cultural Analysis.
She has been covering sports, health and fitness for the last five years and has created content for outlets including BBC Sport, BBC Sounds, Runner’s World and Stylist. She especially enjoys interviewing those working within the community to improve access to sport, exercise and wellness. Hannah is a 2024 John Schofield Trust Fellow and was also named a 2022 Rising Star in Journalism by The Printing Charity.
A keen runner, Hannah was firmly a sprinter growing up (also dabbling in long jump) but has since transitioned to longer-distance running. While 10K is her favoured race distance, she loves running or volunteering at parkrun every Saturday, followed, of course, by pastries. She’s always looking for fun new runs and races to do and brunch spots to try.