- A new study linked a very low-calorie ketogenic diet to reversed biological aging in people with obesity.
- People with obesity became six years younger, biologically.
- Experts weigh in on the study’s findings below and if it’s really healthy in the long-term.
Obesity has been thoroughly linked to a higher epigenetic age (drivers of modifications to DNA that may lead to chronic illness and, ultimately, a shorter lifespan). A new study found that a very low-calorie ketogenic diet (VLCKD) may both aid in weight loss and reverse the epigenetic age of participants with obesity by six years—while also lowering their risk of conditions like type 2 diabetes and cardiovascular disease. But experts have mixed feelings on the restrictive diet.
Meet the experts: Meghan Garcia-Webb, M.D., a physician triple board-certified in internal medicine, lifestyle medicine, and obesity medicine; and Trista Best, M.P.H., R.D., L.D., a registered dietitian at The Canada Diet
The study, conducted in Spain and published in Nutrients, compared two groups—those with obesity and those with a “normal” weight. Researchers measured biological age with epigenetic clocks (devices that use blood samples to analyze DNA) at the study’s starting point, after 30 days, and again after 180 days.
For at least the first 30 days, the group with obesity followed a VLCKD of 600 to 800 calories structured after the medically-monitored commercial weight loss program called the PronoKal Method. By the end of the 180 days, there was an unspecified progressive reintroduction of food and increased calories. (Typically, the method ends with a low-calorie diet of 800 to 1500 calories per day.)
The VLCKD phase helped participants accomplish ketosis, which is the metabolic process triggered by a low-carb diet that encourages the body to burn fat for energy instead of carbohydrates. Such a process is thought to be at least partially responsible for the study’s results. Even so, it’s important to note that a VLCKD is not enough calories to sustain life for the average person and is not recommended. In fact, experts warn against it.
“In my experience, patients are not able to stay on a low-calorie ketogenic diet for an extended period of time,” says Meghan Garcia-Webb, M.D., a physician triple board-certified in internal medicine, lifestyle medicine, and obesity medicine. “It can set them up for another cycle of yo-yo dieting, and in general, I don’t recommend it.”
What about the diet helped slow down aging, exactly?
The study suggests that a number of factors could have contributed to the reversal of epigenetic age in obese participants. Firstly, it appears that ketosis played a significant role, which “underscores the diet’s potential role in promoting overall health and longevity,” says Trista Best, M.P.H., R.D., L.D., a registered dietitian at The Canada Diet. Researchers also noted that levels of beta-hydroxybutyrate, a byproduct of ketosis, may have also contributed to the changes, as it has been found to boost antioxidant capacity, improve insulin sensitivity, protect brain health, and more. Decreased body mass index due to weight loss also may have played a part, as may have an improved gut microbiome, the study reported.
Limitations to the study’s findings
Dr. Garcia-Webb points out that the study was quite small and “findings are limited and do not assert direct causation or generalizability to a broader population.” Even so, she finds the results “interesting” because, compared to studies that look at the epigenetic aging process after bariatric weight loss surgery, a VLCKD achieved a greater slowdown in aging, “which suggests the effect may be more linked to the nutritional ketosis and diet as opposed to just the weight loss itself.”
Best adds that “it’s essential to approach these findings with caution, considering individual variability and the need for personalized dietary interventions.” Plus, the extreme dietary restrictions associated with the diet can be detrimental to some, and study participants were monitored.
All participants were European caucasians. People with pregnancy, substance abuse, or chronic medication use (except for anti-diabetic therapy) were excluded. It’s unclear if participants remained on a low-calorie diet after research concluded, or if they gained back any weight.
Dangers of a very low-calorie keto diet
Having between 600 and 800 calories is about as extreme as low-calorie diets get, which poses risk of not meeting nutrient needs (keto seriously cuts back on the entire food category of carbohydrates, after all), muscle loss, mental fog, and gallstones, according to the Academy of Nutrition and Dietetics. Keto side effects also may include keto flu (short-term flu-like symptoms linked to those starting a keto diet), constipation, diarrhea, dehydration, fatigue, and kidney and heart health challenges.
“Any dietary change patients make, I want them to be able to continue doing for decades,” Dr. Garcia-Webb adds. “If someone can’t see themselves doing a low-calorie ketogenic diet when they are 80, then I wouldn’t advise starting now.” She adds that long-term keto eating also significantly increases the risk of high cholesterol if patients eat a lot of animal-based saturated fats. And again, such restrictive eating is not ideal.
In other words, there are different ways to lose weight and become healthier that don’t run the same risks as the diet followed in this study. “People can achieve a healthier body with less extreme measures that provide a more enjoyable, sustainable quality of life,” Dr. Garcia-Webb concludes. “There’s less utility to living longer if people are miserable.”