Medical Bulletin 16/ April/ 2025

Reducing carbohydrate intake even without cutting overall calories may deliver the same metabolic benefits as intermittent fasting, according to new research from the University of Surrey. Published in the European Journal of Nutrition, the study suggests a less restrictive alternative to popular fasting diets.

Researchers observed adults aged 20 to 65 who were classified as overweight or obese. Participants were asked to follow three different diet plans on separate days: a standard diet with typical carbohydrate levels, a low-carb diet with regular calorie intake, and a low-carb diet with significant calorie restriction. Remarkably, both low-carb diets led to measurable improvements in metabolic markers, regardless of calorie reduction.

The study found that reducing carbohydrates helped lower levels of triglycerides, fats in the blood linked to heart disease and prompted the body to shift toward burning fat for energy, a metabolic effect commonly associated with short-term fasting. According to Dr. Adam Collins, Associate Professor of Nutrition and co-author of the study, this suggests that periodic carbohydrate restriction may be a more practical and sustainable way for individuals to manage metabolic health without the demands of extreme calorie cuts.

Interestingly, although participants reported greater hunger on low-carb days, they did not consume more food in the days that followed. This may indicate an adaptive response in the body, suggesting that reduced carbohydrate intake could be easier to maintain long term than previously thought.

These findings could have significant implications for managing chronic conditions like type 2 diabetes, obesity, and heart disease. By offering a dietary approach that is both effective and easier to follow, the study challenges the idea that fasting is the only path to metabolic improvement and opens the door to simpler strategies rooted in everyday nutrition.

Reference: “Isolating the acute metabolic effects of carbohydrate restriction on postprandial metabolism with or without energy restriction: a crossover study” by Hayriye Biyikoglu, M. Denise Robertson and Adam L. Collins, 20 March 2025, European Journal of Nutrition.

DOI: 10.1007/s00394-025-03646-5

A new guideline to help health care providers manage obesity in children and adolescents takes a patient-centred approach, emphasizing behavioural and psychological supports that focus on outcomes valued by patients and their families. The guideline based on the latest evidence, is published in Canadian Medical Association Journal.

It was developed by Obesity Canada through an extensive, 4-year-long collaboration involving adolescents and caregivers with lived obesity experience, methodologists, health care providers, and more than 50 multidisciplinary experts.

These outcomes include quality of life, mental health, related cardiovascular risk factors, avoiding harms, and more.

Pediatric obesity is a complex, chronic, progressive, and stigmatized condition that increases risk for more than 200 health conditions. International data indicate that severe obesity appears to be on the rise globally.

The guideline contains 10 recommendations, including guidance on nutritional, physical activity, psychological, and technology interventions, and medications and surgical options, as well as 9 good practice statements. The authors recommend combining at least 2 options to help manage obesity.

“The guideline is designed to support shared and informed clinical decision-making rooted in systematic, interpretable summaries of scientific evidence,” said Dr. Bradley Johnston, associate professor of nutrition and health research methods and co-chair of the guideline development committee. “To achieve that, we devised a transparent process to assess the totality of scientific evidence for relevant interventions to manage pediatric obesity, while prioritizing outcomes that matter the most to children, adolescents, and their families.”

Reference: Managing obesity in children: a clinical practice guideline

Geoff D.C. Ball, Roah Merdad, Catherine S. Birken, Tamara R. Cohen, Brenndon Goodman, Stasia Hadjiyannakis, Jill Hamilton, Mélanie Henderson, John Lammey, Katherine M. Morrison, Sarah A. Moore, Aislin R. Mushquash, Ian Patton, Nicole Pearce, Joshua K. Ramjist, Tracy Rhyason Lebel, Brian W. Timmons, Annick Buchholz, Jennifer Cantwell, Jennifer Cooper, Julius Erdstein, Donna Fitzpatrick-Lewis, Dawn Hatanaka, Patrice Lindsay, Tasneem Sajwani, Meghan Sebastianski, Diana Sherifali, Julie St. Pierre, Muhammad Usman Ali, Jessica Wijesundera, Angela S. Alberga, Christine Ausman, Trisha C. Baluyot, Emily Burke, Kara Dadgostar, Bronwyn Delacruz, Elizabeth Dettmer, Maegan Dymarski, Zahra Esmaeilinezhad, Ilona Hale, Soren Harnois-Leblanc, Josephine Ho, Nicole D. Gehring, Marsha Kucera, Jacob C. Langer, Amy C. McPherson, Leen Naji, Krista Oei, Grace O’Malley, Angelica M. Rigsby, Gita Wahi, Ian S. Zenlea, Bradley C. Johnston

CMAJ Apr 2025, 197 (14) E372-E389; DOI: 10.1503/cmaj.241456

A new study has concluded that the spike in LDL cholesterol often seen in people on the ketogenic diet does not necessarily increase their risk of heart disease—provided they are otherwise metabolically healthy.

Published in the Journal of the American College of Cardiology: Advances, the research followed 100 adults classified as Lean Mass Hyper-Responders (LMHRs), individuals who experience significant increases in LDL and apolipoprotein B (ApoB) levels while on a ketogenic diet. Despite these elevated markers, participants maintained healthy blood pressure, low triglycerides, low body fat, low insulin resistance, and high HDL (“good” cholesterol) over the course of one year.

The study found no link between the increased cholesterol and heart disease risk in these individuals. Instead, the presence of pre-existing arterial plaque was identified as a more accurate predictor of future cardiovascular issues—suggesting that baseline heart health matters more than cholesterol levels alone in otherwise healthy individuals following a keto diet.

This challenges the long-standing belief that LDL levels alone should dictate cardiovascular risk, and supports a more nuanced, personalized approach to heart health assessments, especially in people adhering to low-carb, high-fat diets.

While the ketogenic diet has shown promise in areas such as epilepsy management, Alzheimer’s prevention, and even enhancing chemotherapy, it has also drawn criticism—most notably for its environmental impact and potential links to type 2 diabetes risk. However, this latest study offers reassurance for keto followers who are metabolically healthy but concerned about cholesterol.

Reference: Soto-Mota, A., Norwitz, N. G., Manubolu, V. S., Kinninger, A., Wood, T. R., Earls, J., ... & Budoff, M. (2025). Plaque Begets Plaque, ApoB Does Not: Longitudinal Data From the KETO-CTA Trial. JACC: Advances, 101686.