ZOE Science & Nutrition

Episode: Lose Weight by Controlling These Hormones | Dr. Andrew Jenkinson (Oct 9, 2025)

Host: Jonathan Wolf
Guest: Dr. Andrew Jenkinson, Bariatric Surgeon and Author

Episode Overview

This episode tackles the science behind weight gain, obesity, and the actual impact of hormones on long-term weight regulation. Dr. Andrew Jenkinson, a leading bariatric surgeon, discusses why calorie counting and willpower alone don't work, the role of genetics versus environment, and how hormones like leptin and insulin play a central role. The conversation provides practical steps for lasting weight loss, debunks myths, and offers empowering, actionable advice.

Main Themes

• Why calorie counting and diets fail for most people
• The true roles of genetics, environment, and epigenetics in weight
• How the brain's hypothalamus sets your "weight set point"
• The central role of hormones, especially leptin and insulin
• Practical strategies to lower your set point and achieve sustainable weight loss
• Impact of stress, sleep, and exercise beyond just food choices
• The promise and pitfalls of new weight loss drugs

Key Discussion Points & Insights

1. Rapid-Fire Myths and Facts on Obesity (00:41–01:38)

• Weight gain is NOT inevitable with age
  “Is gaining weight as we age inevitable? No for most people.” (00:53 – Dr. Jenkinson)
• Calorie counting doesn’t work for long-term weight loss
  “Will calorie counting work for long term weight loss? No.” (01:07 – Dr. Jenkinson)
• Hormones can make us overeat
  “Can our hormones cause us to overeat? Yes.” (01:11 – Dr. Jenkinson)
• Obesity should be considered a disease
• Many people can lose weight and keep it off without drugs
• Metabolism slows after weight loss
• Biggest myth: “Losing weight is all about calories.”

2. The Obesity Epidemic: More than Willpower or Genes (02:16–07:00)

• The old “eat less, move more” advice is not supported by science

• Obesity is not simply a willpower or moral failing; it’s a physiological response to the environment

• Drastic rise in obesity rates over 30 years is NOT due to genetic change—genes have not shifted, but our food and stress environments have changed dramatically

  “Is that a sudden lack of willpower amongst that population?... These are the questions we've got to ask about why suddenly the population is really struggling with obesity.”
  (03:37 – Dr. Jenkinson)

• Genetics explain about 70% of obesity risk, but only when triggered by environmental factors (processed food, stress, etc.)

• Twin studies: Even raised apart, identical twins have similar weights, showing the strong genetic component—but genes alone can’t explain recent trends

3. Epigenetics: How the Womb Prepares Us for the World (06:50–10:14)

• Epigenetics: The environment in the womb can activate or silence genes based on expectations of the outside world

• Dutch Famine Study: Babies exposed to famine in utero had higher rates of obesity decades later, because their bodies were “programmed” for famine but lived in abundance

  “The fetus is marinating in preparation for the environment that it predicts.”
  (10:01 – Dr. Jenkinson)

• Willpower or postnatal environment alone do not explain these changes

4. Why Diets Fail: The "Set Point" and the Hypothalamus (10:28–16:40)

The Weight Set Point (WSP)

• The hypothalamus in the brain tightly regulates your body's weight set point, driving you to stay within a particular weight range

• When dieting:

  • Short-term weight loss is possible
  • Long-term, the body fights back—slows metabolism, increases hunger, and “pulls” weight back to set point

• Weight cycling (yo-yo dieting) can actually raise your set point over time, leading to higher weight gain

  “You can hold your breath for a while, but you're never gonna be able to stop breathing.”
  (13:01 – Dr. Jenkinson)

Powerful Metaphors:

• Elastic anchor: Losing weight with diets is like pulling an anchored boat with an elastic rope—harder you pull, harder it snaps back (15:00)
• After rebound, you often gain more:
  “I always put it back on and more, they all say.” (16:53 – Dr. Jenkinson)

5. The Basal Metabolic Rate (BMR) – The Hidden Driver (20:12–23:31)

• Basal metabolism makes up ~70% of daily energy expenditure, is dynamic, and mostly outside conscious control

  • If you cut calories, your basal metabolism adapts—burning less energy and making continued weight loss impossible long-term
  • Overeating slightly increases metabolism, but not enough to offset major lifestyle/environmental changes

  “That metabolic dimmer switch is gonna be turned down and your body is just gonna adapt to the low calorie intake...”
  (22:58 – Dr. Jenkinson)

• Doctors often blame patients for “cheating” on diets without recognizing this metabolic adaptation

6. Hormonal Miscommunication: Leptin & Insulin (28:46–35:21)

Leptin: The Master Appetite Controller

• Leptin, secreted by fat cells, signals the brain about stored energy
  • High leptin: “tank full,” suppress appetite, increase metabolism
  • Low leptin: “tank empty,” trigger hunger, slow metabolism

Leptin Resistance: Why the Message Gets Lost

• In obesity, leptin levels are high, but the brain becomes leptin resistant

  • Insulin (raised by sugar/processed carbs) blocks leptin’s signal
  • Brain “thinks” the tank is empty, triggers inappropriate hunger and low metabolism

  “When you got leptin resistance, you become hungry and you become quite tired because your metabolic rate has been turned down. It totally flips the whole concept on its head.”
  (34:42 – Dr. Jenkinson)

• This is why being labeled as "lazy" or "greedy" is completely backwards—those traits are outcomes of hormonal dysregulation, not causes

Powerful Analogy:

• Empty gas tank: Leptin resistance is like a broken fuel gauge—tank is full, but warning light won't turn off (35:50)

7. Practical Steps: How to Lower Your Set Point (37:30–45:28)

4-Step Approach

1. Quit Sugar (First Month)

   • Sugar is the “enemy”—quitting reduces insulin and begins to restore leptin function
   • May require willpower at first due to its addictive qualities

2. Stop Snacking (Second Month)

   • Shift to three structured meals a day; embrace “real” hunger (don’t snack)

   “Try and embrace hunger. Do what the French do, don't snack between meals, but eat really, really well and enjoy food when you're having the meal.”
   (38:00 – Dr. Jenkinson)

3. Ditch Processed Foods (Third Month)

   • Highly processed foods drive insulin higher and set point upward

   “The problem with processed foods is ... they metabolically cause chaos in your body.”
   (40:08 – Dr. Jenkinson)

4. Reduce Carbohydrate Intake

   • From ~300g/day down towards 100g or less as tolerable to minimize insulin spikes

   “This is going to have a really good effect on our insulin. So lowish carbohydrate dieting, that is tolerable? Yes, if you combine that with time restricted eating as well. Well, fantastic.”
   (45:22 – Dr. Jenkinson)

8. Mindful Eating & Time Restricted Eating (40:55–44:28)

• Mindful Eating:

  • Savor meals, prepare food consciously, pay attention to hunger cues
  • Avoid “mindless” processed food consumption and break dopamine-driven eating cycles

  “If you understand ... how good well prepared natural foods can taste ... that's a really important part of it.”
  (42:11 – Dr. Jenkinson)

• Time Restricted Eating:

  • Eating within a daily window (6–8 hours), fasting the rest of the day
  • Helps lower insulin, releases leptin signal, improves appetite regulation

  "The more you can fast per day, the more effective the time restricted eating will be..."
  (44:02 – Dr. Jenkinson)

9. Beyond Food: Stress, Sleep & Exercise (47:07–48:23)

• Stress (Cortisol):

  • Chronic stress raises cortisol, increasing insulin and blocking leptin
  • De-stressing (resolving life issues, practicing relaxation) is vital

• Exercise:

  • Not mainly for calorie burning—improves insulin sensitivity, lowers stress
  • Should be enjoyable to be sustainable

• Sleep:

  • Poor sleep = higher stress hormones and weight gain risk

10. The Role and Risks of Weight Loss Drugs (45:28–47:07)

• GLP-1 Agonists (e.g., Ozempic):

  • Suppress appetite, lead to significant weight loss
  • However, stopping the drugs usually leads to rapid regain—sometimes more than starting weight
  • Best strategy: Use drugs briefly to change habits and then maintain weight with lifestyle

  "Use the drug the smart way... change your eating behavior... then you're more likely to be able to come off the drug and not regain weight."
  (46:44 – Dr. Jenkinson)

11. The One Crucial Advice (48:23–48:49)

“It's not the calories in the food, it's what the food does to you metabolically. So avoid sugar, avoid refined carbohydrates, avoid processed food, don't snack all the time. You will lose a lot of weight just by doing that.”
(48:33 – Dr. Jenkinson)

Memorable Quotes & Notable Moments

• On the calorie myth:

  “The most common myth about obesity that you hear? ... That losing weight is all about calories.” (01:36)

• The reality of dieting:

  “The best way to put weight on is to go on a diet. Low calorie diet, long term.” (30:19)

• On hunger cues:

  “We need to really actually start to embrace hunger because as the French say, hunger is the best sauce.” (43:00)

• On policy:

  “If processed food and sugar were taxed like tobacco and alcohol, and tax revenue went to education, obesity would start to come down naturally.” (53:01)

Key Timestamps

• 00:41–01:38: Rapid-fire myths/facts
• 03:49–06:49: Genetics vs. environment—why obesity rates have changed
• 07:00–10:14: Epigenetics & Dutch Famine study
• 10:28–16:40: Why diets fail—the body’s weight “set point”
• 20:12–23:31: Basal metabolic rate and its role in weight regulation
• 28:46–35:21: Leptin, insulin, and hormone-driven appetite control
• 37:30–45:28: Practical step-by-step plan to lower your set point
• 40:55–44:28: Mindful eating and time-restricted eating
• 47:07–48:23: Stress, exercise, sleep as supporting pillars
• 45:28–47:07: Modern weight loss drugs—pros and cons

Summary Takeaways

• Long-term weight loss isn’t about calorie counting, but about fixing your set point by addressing hormones, especially insulin and leptin.
• Processed foods, sugar, constant snacking, and chronic stress all push up your set point and make you hungrier and more tired.
• The solution: gradually remove sugar, snacks, and processed carbs from your diet, become mindful about eating, shorten your eating window, de-stress, and prioritize sleep.
• Drugs can be a tool, not a cure—lasting change requires habit and environment shifts.
• Sustainable weight loss is eating quality, whole foods with attention, and managing your hormonal environment through food and lifestyle.

For anyone struggling with weight or supporting someone who is, this episode reframes the conversation from willpower and calories to practical, science-based changes that tackle the problem at its root: your hormones and your environment.