What is Fat?

When you hear the word fat, what comes to mind?

1. Do you picture excess weight on your abdomen, waist, or thighs?
2. Or do you associate it with health issues like heart disease or cancer?

While fat often has a negative reputation, it’s much more than just a potential health risk. It is the most calorie-rich macronutrient, breaking down into fatty acids to provide energy for the body. Despite being criticized by diet culture, it plays a crucial role in making meals satisfying and supports many vital functions in the body.

Key Roles of Fat

• Energy Source: Fat provides more calories per gram (9 kcal) than carbohydrates or protein.
• Satisfaction Factor: It enhances the flavor and texture of meals, making them more enjoyable.
• Essential Functions: Beyond energy, it supports cell structure, hormone production, and nutrient absorption (e.g., vitamins A, D, E, and K).

Terms to Know

1. Adipose Tissue:
   • The scientific term for body fat. It stores energy, insulates the body, and cushions organs.
2. Dietary Fats:
   • It found in food, including healthy fats (e.g., omega-3s) and unhealthy fats (e.g., trans fats).
3. Triglycerides:
   • The most common form of fat in the body and food. Triglycerides are composed of fatty acids and glycerol, serving as the body’s main energy storage system.
4. Fatty Acids:
   • The building blocks of fat molecules. They are chains of carbon, hydrogen, and oxygen that determine the type and function of fat.
5. Lipids:
   • The chemical family name for fats and related compounds, such as cholesterol. Derived from the Greek word lipos (meaning fat), lipids include both:
     • Liquid fats: Called oils (e.g., olive oil, fish oil).
     • Solid fats: Simply referred to as fats (e.g., butter, lard).

The Role of Fat in the Body

1. Provides Essential Fatty Acids:
   • Dietary fat supplies the body with essential fatty acids—compounds that the body cannot produce on its own and must obtain through food.
2. Absorbs Fat-Soluble Vitamins:
   • It is necessary for the absorption of vitamins A, D, E, and K, which are crucial for overall health and well-being.
3. Supports Hormone Production:
   • Fats are vital for creating hormones that regulate various bodily functions.
4. Promotes Healthy Skin and Hair:
   • It plays a key role in maintaining healthy skin and shiny, nourished hair.
5. Essential for Brain Health:
   • The brain is composed of about 60% fat, making dietary fats crucial for cognitive function, memory, and overall brain health.

Types of Dietary Fats and Fatty Acids

Dietary fats are categorized based on their chemical structure, which determines their physical state, sources, and health impact. Below are the key types of dietary fats:

1. Saturated Fats

• Sources:
  Found predominantly in animal products like meat, dairy, and some plant-based oils (e.g., coconut oil). Saturated fats are solid at room temperature.
  • Examples: Butter, ghee, coconut oil, cured meats, sausages, bacon, cheese.
• Health Implications:
  Overconsumption of saturated fats is linked to obesity and related health issues in adults.
• Recommended Intake:
  • Saturated fats: Limit to under 10% of total fat consumption daily (as advised by international health authorities like those in the US and UK).
  • Total fat: Should comprise less than 30% of total energy intake.

2. Trans Fats

• Sources:
  • Naturally present in small amounts in milk and meat.
  • Most trans fats are industrially produced through hydrogenation, turning liquid unsaturated fats into stable solids.
  • Common in deep-fried foods and processed items.
  • Examples: Fried foods, commercial baked goods, frozen pizza, crackers, margarine.
• Health Implications:
  Trans fats are the worst fats for health. They:
  • Raise “bad” LDL cholesterol.
  • Lower “good” HDL cholesterol.
  • Increase the risk of heart disease.

3. Monounsaturated Fats (MUFA)

• Sources:
  These fats are liquid at room temperature and primarily found in plant-based oils and some nuts.
  • Examples: Olive oil, peanut oil, canola oil, avocados, pumpkin seeds, pecans.
• Health Benefits:
  • Promote good cholesterol (HDL) levels.
  • Reduce bad cholesterol (LDL) levels.
  • Lower the risk of heart disease.
• Recommendation:
  Replace saturated and trans fats with monounsaturated fats wherever possible.

4. Polyunsaturated Fats (PUFA)

• Types:
  Includes omega-3 and omega-6 fatty acids, which the body cannot produce on its own.
• Sources:
  Found in both animal and plant-based foods.
  • Examples:
    • Plant sources: Soybeans, soybean oil, sunflower oil, sunflower seeds, walnuts, flaxseeds.
    • Animal sources: Salmon, tuna, herring, mackerel, trout.
• Health Benefits:
  • Essential for brain function, cell structure, and reducing inflammation.
  • Omega-3 fatty acids are particularly beneficial for heart health.

What is Cholesterol?

Cholesterol is often misunderstood as something harmful, but it is an essential molecule for the body. While many people worry about their cholesterol levels or dietary cholesterol intake, the reality is more nuanced.

Key Facts About Cholesterol

1. Essential for the Body:
   • Cholesterol is necessary for building cell membranes and producing important structures like hormones.
   • It is not inherently bad; the body needs cholesterol to function properly.
2. Cholesterol Production:
   • Most cholesterol in the body is produced by the liver and does not come directly from food.
   • Dietary cholesterol, such as that found in eggs, is not well absorbed by the gut and has minimal impact on blood cholesterol levels.
3. Controlled by Feedback Mechanisms:
   • Cholesterol production in the body is regulated by a feedback system that keeps levels balanced.
   • High cholesterol levels are often determined by genetics, not solely by diet. So if your cholesterol is elevated, it may have more to do with your genes than your daily omelet.

Cholesterol and the Bloodstream

• How Cholesterol Travels:
  Cholesterol, like other fats, cannot move through the water-based bloodstream on its own. Instead, it binds to lipoproteins, which act as carriers.
• Cholesterol Testing:
  When you get a “cholesterol test” or “lipid profile,” what is being measured are the lipoproteins that carry cholesterol and triglycerides in your blood.
• Not All Lipoproteins Are Equal:
  Different types of lipoproteins have varying impacts on health, such as:
  • LDL (Low-Density Lipoprotein): Often referred to as “bad cholesterol” because high levels can lead to plaque buildup in arteries.
  • HDL (High-Density Lipoprotein): Known as “good cholesterol” because it helps remove excess cholesterol from the bloodstream.

Lipoproteins: The Body’s Fat Transporters

Lipoproteins are molecules that transport fats (lipids) through the bloodstream. They vary in size, density, and function, which determines their role in the body and their impact on health.

1. Chylomicrons

• Formation: Produced in the intestinal cells, where fat particles are absorbed and repackaged within the endoplasmic reticulum (ER).
• Function:
  • Transport dietary fats to the liver.
  • Once processed by the liver, fats are converted into triglycerides or released as other lipoproteins.

2. Very Low-Density Lipoproteins (VLDLs)

• Composition:
  • Mostly triglycerides, with some cholesterol and minimal protein.
  • The high lipid content makes them less dense.
• Function:
  • Produced in the liver.
  • Deliver triglycerides to cells for energy or storage.
  • As triglycerides are delivered, VLDL becomes richer in cholesterol and protein, eventually transforming into LDL.

3. Low-Density Lipoproteins (LDLs)

• Composition:
  • Higher cholesterol content compared to triglycerides and protein.
  • Denser than VLDL due to its reduced lipid content.
• Function:
  • Carries cholesterol to cells that need it for functions like cell membrane production and hormone synthesis.
• Health Impact:
  • Referred to as “bad cholesterol” because elevated LDL levels can lead to plaque buildup in blood vessels, increasing the risk of cardiovascular diseases.

4. High-Density Lipoproteins (HDLs)

• Composition:
  • Richer in protein, with less cholesterol, making them the densest lipoproteins.
• Function:
  • Produced in the liver and intestine.
  • Collect cholesterol from cells and transport it back to the liver for processing or excretion.
• Health Impact:
  • Known as “good cholesterol” because it helps reduce cholesterol buildup in blood vessels, lowering the risk of heart disease.

Effects of Diet on Lipoproteins

Diet has a significant impact on lipoprotein levels, influencing overall cholesterol and fats transport in the body. While individual responses to dietary changes vary, some general trends apply to most people.

Key Dietary Impacts on Lipoproteins

1. Omega-3 Polyunsaturated Fatty Acids:
   • Found in fatty fish (e.g., salmon, mackerel, and sardines), flaxseeds, walnuts, and chia seeds.
   • Effect:
     • Lowers LDL cholesterol (“bad cholesterol”).
     • Increases HDL cholesterol (“good cholesterol”).
2. Saturated Fat:
   • Found in foods like butter, cheese, red meat, and coconut oil.
   • Effect:
     • Raises LDL cholesterol and triglycerides, which can increase the risk of heart disease.
3. Processed Foods:
   • Includes items like fried snacks, sugary beverages, packaged baked goods, and processed meats.
   • Effect:
     • Worsens lipoprotein profiles by increasing LDL cholesterol and triglycerides while reducing HDL cholesterol.
4. Minimally Processed Whole Foods:
   • Includes fruits, vegetables, nuts, seeds, lean proteins (e.g., fish, chicken, tofu), whole grains, beans, and legumes.
   • Effect:
     • Improves lipoprotein profiles by supporting higher HDL cholesterol levels and lowering LDL cholesterol and triglycerides.

Fat is neither inherently good nor bad; its effects depend on the type, source, and amount consumed. Prioritizing healthy fats and reducing saturated and trans fats can help maintain cholesterol balance, heart health, and overall well-being.