#537: Appetite Regulation, Metabolic Compensation and More – Stephan Guyenet, PhD
Oct 1, 2024
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Dr. Stephan Guyenet, an expert in obesity neuroscience and eating behavior, dives into the complexities of appetite regulation and metabolism. He discusses how liposuction affects leptin levels and hunger, along with long-term impacts of crash diets on appetite. Fascinatingly, he explores the concept of the 'brain microbiome' and its potential role in obesity. Guyenet also critiques weight management strategies, suggesting that drugs and bariatric surgery may be essential in today's environment, while emphasizing the need for a sustainable approach to health.
Liposuction may initially lower leptin levels, but this reduction can ultimately lead to increased hunger and weight regain over time.
Chronic energy restriction triggers the brain's adaptive response, increasing hunger and potentially reducing energy expenditure without indicating long-term appetite dysfunction.
Genetic factors significantly influence the unique appetite regulation observed in individuals with anorexia and pronounced obesity, complicating traditional metabolic compensation models.
Deep dives
Impact of Liposuction on Leptin Levels
Liposuction leads to a variable reduction in leptin levels, which is surprising given that leptin is typically proportional to fat mass. While this reduction may initially improve leptin resistance, the drop in leptin could increase hunger over time. Studies consistently show that after fat loss, a homeostatic reaction occurs, prompting the body to regain fat to return to baseline levels. Thus, while liposuction can accomplish aesthetic goals, it is not effective for long-term fat loss.
Chronic Energy Restriction and Appetite Regulation
Chronic energy restriction or crash dieting activates the brain’s regulatory system, which opposes fat loss by increasing hunger and possibly reducing energy expenditure. This does not signify appetite dysregulation in the long term, as evidence shows that individuals regulated their appetite normally after initial weight loss. Long-term follow-ups from weight loss trials indicate that diets do not leave individuals worse off than if they had never attempted to lose weight at all. Therefore, the observed increases in appetite post-dieting are normal adaptive responses rather than indications of a dysfunctional system.
Metabolic Compensation in Anorexia and Obesity
Individuals with anorexia and morbid obesity often illustrate a complex relationship with metabolic compensation, defying conventional understanding. In anorexia, affected individuals may not adequately respond to hunger cues despite their physical state, while those with obesity may regulate fat mass at an elevated set point. Genetic factors significantly contribute to both conditions, with a substantial genetic influence on body mass index observed. Current literature suggests that the regulatory system functions differently in these individuals, with the brain’s signaling mechanisms adjusting to their unique circumstances.
Role of Serotonin and Drugs in Appetite Control
Medications like serotonin and dopamine reuptake inhibitors can influence appetite by altering neural pathways that regulate hunger. For instance, bupropion engages POMC neurons in the hypothalamus that are crucial for appetite suppression. However, the effects of serotonin on appetite are complex, with different serotonin-targeting drugs having varying outcomes on weight. Understanding how these medications impact appetite can provide insights into their potential use for weight management.
Public Health Policies and Weight Management
There is an ongoing debate about the efficacy of public health interventions against obesity, highlighting the limited success of upstream strategies like community gardens and nutrition education. Evidence suggests that bariatric surgeries and pharmacological treatments are more effective for weight loss, raising questions about the allocation of resources towards less impactful interventions. Effective public health strategies may include aggressive taxation on unhealthy foods and better marketing regulations, particularly for children. The potential effectiveness of robust, evidence-based strategies warrants further discussion on their acceptability within public policy frameworks.
This is an “ask me anything” (AMA) episode with Dr. Stephan Guyenet, an expert in obesity neuroscience and eating behavior. This episode was originally published on Sigma Nutrition Premium. If you’re interested in subscribing to Sigma Nutrition Premium, then check all the details here.
Questions Answered:
[04.27] If we surgically remove adipose tissue, do leptin levels suddenly drop? How would this impact hunger over time?
[06.56] How does chronic energy restriction (or following a crash diet) affect long-term appetite regulation?
[13.21] How do anorexia and pronounced obesity defy the rules of metabolic compensation?
[24.12] Why do some SDRIs (serotonin–dopamine reuptake inhibitors) reduce hunger/appetite?
[28.02] Can an algorithm really decipher someone’s “ideal weight?
[33.08] Could the “brain microbiome” impact appetite regulation and/or obesity?
[35.34] In our current environment, are the only efficacious interventions drugs and bariatric surgery?
[46.01] What should we make of claims by Gary Taubes about insulinogenic foods?
[52.37] Is there a maximum duration someone should spend in fat loss (or weight gain) phases?
[53.43] Why do some people struggle to gain weight?
