Body Composition & DEXA

Many of us use body weight or BMI (body mass index) for a quick approximation of our health status. Yet the utility of these metrics is limited because they provide little information about a far more relevant parameter: body composition – and in particular, body fat and its distribution. Body weight and BMI alone do not discriminate between muscle mass (which we want to maintain or increase to promote longevity) and fat mass (which we generally want to keep relatively low). Thus, when we set a goal to “lose weight,” our real aim ought to be losing fat.

Losing fat mass isn’t necessarily easy, but unfortunately, that struggle pales in comparison to the challenge of keeping it off. This is caused in large part by a hormone called leptin, which is secreted by fat cells and plays a critical role in numerous endocrine pathways and functions, including the regulation of energy homeostasis. Leptin is secreted at levels proportional to body fat and acts as a “satiety hormone” in the brain, causing a reduction in food intake. However, as leptin signaling decreases – due to fat loss or to key neurons becoming leptin-resistant – the brain interprets this as a sign of starvation, and drives increased appetite and reduced energy expenditure to counteract the loss.

The content selections below provide more information on the accumulation and measurement of body fat, different types of fat and their relative impacts on health, and the effects of leptin on appetite and metabolism.

Ask Me Anything (AMA)

AMA

Applying the tools of longevity in the real world: disease prevention, DEXA scans, artificial sweeteners, injury recovery, stability training, habit formation, protein intake and mTOR activation, and more

Ep. #385 (AMA #82)

Longevity

AMA

Biological aging tests, longevity training, emerging therapies, GLP-1 RAs, sun exposure, and more

Ep. #383 (AMA #81)

Exercise

Guest Episode

Women’s health and performance: how training, nutrition, and hormones interact across life stages

Ep. #378 with Abbie Smith-Ryan, Ph.D.

Longevity

AMA

Longevity interventions, exercise, diagnostic screening, and managing high apoB, hypertension, metabolic health, and more

Ep. #376 (AMA #78)

Nutrition

Guest Episode

The ketogenic diet, ketosis, and hyperbaric oxygen: metabolic therapies for weight loss, cognitive enhancement, cancer, Alzheimer’s disease, brain injuries, and more

Ep. #375 with Dominic D’Agostino, Ph.D.

Nutrition

Guest Episode

The protein debate: optimal intake, limitations of the RDA, whether high-protein intake is harmful, and how to think about processed foods

Ep. #368 with David Allison, Ph.D.

Exercise

Guest Episode

Training for longevity: A roundtable on building strength, preventing injury, meeting protein needs, guidance for women and youth athletes, and more

Ep. #365 with Gabrielle Lyon, Mike Boyle, Jeff Cavaliere

Nutrition

AMA

Diets: how to evaluate and implement any diet including keto, carnivore, vegan, Mediterranean, and more

Ep. #364 (AMA #75)

Exercise

AMA

Preserving brain health, optimizing exercise programming, improving body composition, and more

Ep. #356 (AMA #73)

Nutrition

AMA

Fasting: benefits for body composition and disease prevention, potential risks, and Peter’s updated practical framework

Ep. #353 (AMA #72)

Longevity

AMA

Fasting, well-balanced diets, alcohol, exercise for busy people, wearables, emotional health, assessing cardiovascular health, and more

Ep. #336 (AMA #68)

Exercise

Guest Episode

Optimizing endurance performance: metrics, nutrition, lactate, and more insights from elite performers

Ep. #331 with Olav Aleksander Bu

Longevity

AMA

Special AMA: Peter on exercise, important labs, building good habits, promising longevity research, and more

Ep. #329

Nutrition

AMA

Optimizing nutrition for health and longevity: myth of a “best” diet, complexities of nutrition science, and practical steps for building a sustainable diet

Ep. #328 (AMA #66)

Risks

Podcast Summary

Peter’s key takeaways on bone health, calorie restriction, gene editing and more

Ep. #325

Nutrition

Guest Episode

Metabolism, energy balance, and aging: How diet, calorie restriction, and macronutrients influence longevity and metabolic health

Ep. #324 with Eric Ravussin, Ph.D.

Medications & supplements

AMA

New insights on GLP-1 agonists (Ozempic, Wegovy, Mounjaro)

Ep. #320 (AMA #64)

Nutrition

Guest Episode

Rethinking nutrition science: the evolving landscape of obesity treatment, GLP-1 agonists, protein, and the need for higher research standards

Ep. #314 with David Allison, Ph.D.

Nutrition

AMA

Protein’s impact on appetite and weight management, and uric acid's link to disease and how to manage levels

Ep. #313 (AMA #62)

Nutrition

AMA

Preventing cognitive decline, nutrition myths, lowering blood glucose, apoB, and blood pressure, and more

Ep. #306 (AMA #60)

Nutrition

Premium Article

Body composition: impact on disease risk and how to assess and improve it

Nutrition

Guest Episode

Optimizing muscle protein synthesis: the crucial impact of protein quality and quantity, and the key role of resistance training

Ep. #299 with Luc van Loon, Ph.D.

Nutrition

Free Article

Does time-restricted eating increase the risk of cardiovascular death?

Nutrition

Premium Article

Optimizing protein quantity, distribution, and quality