Controlling Sugar Cravings & Metabolism with Science-​​Based Tools

Sugar and the Nervous System

• Sugar is not inherently bad, but consuming a lot of refined sugars, especially high fructose corn syrup, can have negative effects on the brain and body
• Calories in, calories out principle: if we ingest more energy than we burn, we gain weight; if we ingest less energy than we burn, we lose weight; if the two are balanced, we maintain weight
• Sugar impacts the brain in ways that make us crave more sugar and affect our focus, agitation, happiness, and depression
• The nervous system regulates many functions and behaviors related to sugar, such as thinking, exercising, gaining/​​losing weight, and achieving goals

What Happens When We Eat Sugar

• When we ingest sugar, two mechanisms make us crave more sugar
• Ingesting sugar affects neural circuits, impacting focus, agitation, happiness, and depression
• Sugar plays a critical role in achieving goals, but ingesting too much or the wrong forms can impede progress
• The brain responds to sugar intake by regulating various functions and behaviors
  Hormonal Response to Ingesting Food
• Ghrelin: hormone that increases depending on how long it’s been since we ate last 
  • Makes us hungry by interacting with neurons in the arcuate nucleus of the hypothalamus and lateral hypothalamus
  • Ghrelin levels go down when we eat
• Blood glucose (blood sugar) rises when we eat, especially when consuming carbohydrates 
  • Insulin, released from the pancreas, helps regulate blood glucose levels
  • Diabetics (type 1) need to take insulin when they eat to avoid neurotoxicity and other negative effects of high blood sugar
• Neurons in the brain and body use glucose to function, allowing them to fire electrical potentials and communicate with other neurons

Study on Glucose and Brain Function

• Study published in the journal Neuron
• Examined orientation-​​tuned neurons in the visual cortex, which respond to specific angles of lines and are the building blocks for visual perception
• Found that the sharpness and precision of orientation tuning of these neurons is dependent on blood glucose levels 
  • Neurons functioned best when subjects were fed and glucose was available
  • In fasted states, the orientation tuning of neurons became broader, leading to distorted and blurred perception of the outside world

Intermittent Fasting and Focus

• Some people, including the speaker, find that they are more focused during fasted states
• Intermittent fasting involves eating within a specific time window, such as between 11:00 a.m. and 8:00 p.m., and fasting outside of that window
• The speaker suggests that the increased focus during fasted states may be related to the changes in neuronal function observed in the study
  Fasting, Glucose, and Brain Function
• Fasting can lead to mental clarity 
  • Neurons use available fuels (glycogen, fat, blood sugar) from previous food intake
• Neurons love glucose 
  • Properly elevated blood glucose levels allow neurons to work best
• Astrocytes deliver glucose to neurons 
  • Most abundant cell type in the brain
  • Involved in shaping neuronal function and brain plasticity

Fructose vs. Glucose

• Fructose found in fruit and high fructose corn syrup 
  • Fruit has lower concentrations of fructose compared to high fructose corn syrup
• Fructose cannot directly access the brain 
  • Needs to be converted into glucose in the liver
• Fructose reduces hormones that suppress ghrelin (hunger hormone) 
  • Increases ghrelin levels, making us hungrier
• Eating fruit in moderation does not lead to overeating or weight gain 
  • High fructose corn syrup and excessive fructose consumption can negatively impact brain function and appetite regulation
    Fructose and Hunger
• Fructose can suppress pathways that suppress hunger, leading to increased hunger 
• Current recommendations encourage eating more fruits and vegetables
• High fructose corn syrup is not recommended due to its high fructose content
• Some people find that fruit can stimulate their appetite

Sugar and Attraction

• Sugar is attractive due to its taste and its ability to raise blood glucose levels
• Two parallel pathways in the brain control sugar consumption:
• One pathway is related to the perception of sweet taste
• The other pathway is related to the nutritive component of sweet foods (raising blood glucose)
• These pathways are separate from those controlling the desire for savory, salty, or spicy foods

Sweet Taste Perception

• Sweet taste receptors are found on the tongue and palate
• Ingesting something sweet sends signals to the brain, causing a shift in perception of food
• This shift makes sugary foods and other foods appear more appetizing
• Dopamine, a neuromodulator, is involved in motivation and craving for sweet foods
  Nucleus of the Solitary Tract and Sugar Preference
• The nucleus of the solitary tract is crucial for understanding sugar preference 
• Neuropod cells trigger activation of dopamine pathways within the mesolimbic reward pathway
• Signals are conveyed from the gut to the brain when we ingest sweet foods 
  • Not related to the perception of sweetness, but the correlation with increased blood glucose
• This leads to a preference for sweet foods and a desire to eat more

Hidden Sugars and Neuropod Cells

• Hidden sugars are often masked with salt or other flavors to increase consumption
• Savory foods can contain hidden sugars that trigger neuropod cells and increase dopamine, leading to cravings for more food

Three-​​pronged Push for Sugar Consumption

1. Sweet taste of sugary foods
2. Signals from the gut to the brain (neuropod cells)
3. Metabolic consequences of sugary foods 
4. The nervous system is a glucose-​​consuming machine, with at least three pathways pushing us to seek and consume more sugar 

Glycemic Index and Sugar Intake Control

• Glycemic index measures how quickly blood sugar rises after ingesting particular foods 
  • Low glycemic index: <55
  • Medium glycemic index: 55–69
  • High glycemic index: >70
• Ingesting fiber and/​​or fat along with food can reduce the glycemic index
• The context in which food is ingested also matters (e.g., after hard training, high glycemic foods like mangoes can be beneficial)
  Glycemic Index and Dopamine Release
• Neurons prefer glucose for energy 
• Sweet things trigger dopamine release and make us want to eat more
• Sharp rise in blood glucose = more potent dopamine signal
• To reduce sugar cravings, consider:
• Consuming sweet foods with lower glycemic index
• Combining sweet foods with fiber or fat to reduce glycemic index and slow dopamine release

Conditioned Taste Preference

• New area of nutrition neuroscience
• Studies show that pairing a flavor with maltodextrin (which increases blood glucose) can lead to the flavor alone increasing insulin levels
• Controversial findings with artificial sweeteners
• Some studies suggest that artificial sweeteners can also increase insulin levels when paired with maltodextrin
• More research needed, especially on plant-​​based non-​​caloric sweeteners

Reducing Refined Sugars and High Fructose Corn Syrup

• Most people should reduce intake of refined sugars and high fructose corn syrup
• Dr. Robert Lustig’s work highlights the dangers of hidden sugars in processed foods
• Reducing sugary drinks and fruit juices with added sugar is important for overall health
• Emerging research suggests that reducing sweet foods and refined sugars may have additional benefits for healthy individuals
  Artificial Sweeteners and Insulin
• Artificial sweeteners may increase insulin even in the absence of food 
  • Example: Diet soda alone could increase insulin without increasing blood glucose
  • Controversial data due to unusual experimental conditions
• Studies on artificial sweeteners’ impact on gut microbiome mainly done on animals 
  • Disruption to gut microbiome can affect immune health and brain health

Conditioned Flavor Preference

• Ingesting sweet foods can lead to wanting more sweet foods 
  • Also increases desire for glucose-​​elevating foods and food in general
• Useful to understand for those struggling with regulating appetite and sugar cravings

ADHD and Sugar Consumption

• Refined sugar consumption is not good for people with ADHD or attentional issues 
  • However, consuming no glucose is also not ideal
• Meta-​​analysis shows negative outcomes for ADHD symptoms when consuming more than four 12-​​ounce sugary drinks per week 
  • Controversy over whether sugar consumption can cause ADHD
• Omega‑3 fatty acid supplementation can be beneficial for children with ADHD 
  • Can also improve mood and cardiovascular health

Neuropod Cells

• Neuropod cells in the gut detect levels of sugar, amino acids, and essential fatty acids 
  • Communicate this information to the brain through electrical potentials
  • Generic language, not specific to each nutrient type
    Adjusting Blood Glucose Levels
• Lemon juice and lime juice can blunt blood glucose spikes 
  • Possibly due to post-​​ingestive effects of glucose in the gut
  • Sour taste on the tongue can change neural response to sweet foods
• Cinnamon can help control blood sugar 
  • Adjusts the rate of glucose entry into the bloodstream
  • May slow gastric emptying time
  • Limit to 1–1.5 teaspoons per day due to cumidin content
• Berberine is a potent substance for reducing blood glucose 
  • On par with prescription drugs like metformin
  • Can cause hypoglycemia if taken on an empty stomach or with low carbohydrate intake
  • Typical dosage range: 0.5–1.5 grams daily
  • Sodium caprate can augment the effects of berberine
• Maintaining low to moderate blood glucose can lead to long-​​standing changes in neural circuits 
  • May result in reduced sugar cravings over time

Note: Always consult with a medical professional before using potent substances like berberine or metformin to control blood glucose levels.
Controlling Sugar Cravings and Neural Circuits

• Berberine: potent substance for controlling sugar cravings
• Sleep: high-​​performance tool for controlling sugar cravings and neural circuits

Role of Sleep in Sugar Metabolism and Hunger

• Study published in Cell Report 
  • Measured metabolites from people’s breath during sleep
  • Evaluated metabolism in the brain and body during different sleep phases
• Each sleep stage associated with a specific pattern of metabolism 
  • Particular phases of sleep linked to sugar metabolism, fat metabolism, etc.
• Disrupted sleep can increase appetite for sugary foods 
  • Poor sleep quality may disrupt metabolic pathways

Importance of Sleep for Metabolism

• Quality sleep helps regulate appetite and specific forms of metabolism
• Proper sleep essential for immune system function, clear thinking, and regulating sugar metabolism
• Aim for regular, sufficient, high-​​quality sleep at least 80% of the time