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Today, there is growing discussion about the health effects of dietary fat. Many researchers highlight the benefits of fats found in foods such as salmon, avocado, and extra virgin olive oil. At the same time, others continue to debate the role of saturated fat in health. With mixed messages coming from different directions, it can be difficult to understand how fat truly affects the body, especially when the goal is fat loss.

What we do know is this: fat plays an important role in food and metabolism. Fat improves taste, increases satisfaction, and helps people feel full after meals. From butter on bread to oil drizzled on vegetables, fat changes how food is experienced and how the body responds.

Beyond taste, fat has specific biological effects that influence inflammation and insulin (a hormone that helps control how energy is used in your cells and influences whether your body burns fat or sugar for energy)¹ ⁴. These effects matter when the goal is to lose body fat and improve overall health.

To understand why fat can either help or hurt fat loss, we first need to understand what happens inside the body after you eat.

What Happens in the Body After You Eat (The Post-Meal State)

Every time you eat, your body enters a state called the post-meal state. This is the period after food is eaten, during which the body is digesting and absorbing nutrients and deciding how to use or store that energy.

The post-meal state can last anywhere from two to several hours, depending on the type of food eaten and how foods are combined.

During this time, several important things happen:

• • Blood sugar may rise, especially after eating carbohydrates
  • Insulin is released to help move sugar and nutrients into cells
  • Blood vessels adjust how well they relax and deliver nutrients throughout the body
  • Inflammation may increase or decrease, depending on the foods eaten

Blood vessels are not just passive tubes. They are living tissues that respond to what circulates in the blood. After a meal, healthy blood vessels should relax and widen so nutrients and oxygen can be delivered efficiently to muscles and other tissues.

When a meal creates an anti-inflammatory environment, blood vessels tend to stay flexible and responsive, allowing insulin to work efficiently and nutrients to be used properly.

When a meal creates an inflammatory environment, blood vessels may temporarily become stiffer and less able to relax. This can reduce nutrient delivery, make insulin less effective, and keep insulin elevated longer.

Insulin itself is not the problem. The key issue is how long insulin stays elevated and the environment in which it is working. A healthier post-meal environment allows insulin to clear sooner, helping the body return to fat burning more quickly.

Does Blood Sugar Always Rise After Eating?

No. Blood sugar does not rise the same way with every food.

However, all carbohydrates raise blood sugar, some more quickly and more strongly than others.

• • Carbohydrates cause the largest rise in blood sugar, though the size and speed depend on the type of carbohydrate
    • Whole carbohydrates like potatoes, rice, and pasta raise blood sugar
    • Ultra-processed carbohydrates like crackers, pizza, pastries, and refined breads often raise blood sugar faster and higher
  • Protein may cause a small rise or little change in blood sugar
  • Fat causes little to no rise in blood sugar by itself

This matters because rising blood sugar plays a central role in insulin signaling².

Does Insulin Always Rise After Eating?

Yes, insulin is released after most meals, but not to the same extent.

Carbohydrates trigger the largest insulin response because rising blood sugar is the main signal that tells the body to release insulin.

In real life, the largest and longest insulin responses often occur when carbohydrates are eaten together with fat, especially when both the carbohydrates and fats are highly processed.

Examples include:

• • Pizza
  • Pastries
  • Bagels with cream cheese
  • Deep-fried French fries

These foods combine:

• • Refined or ultra-processed carbohydrates, which raise blood sugar quickly
  • Added fats, which slow digestion and keep insulin elevated longer

This combination often leads to both a higher insulin response and a longer period of elevated insulin levels compared to eating carbohydrates alone.

To clearly separate the effects of each macronutrient:

• • Carbohydrates cause the largest insulin response, with more processed carbohydrates generally triggering a higher and longer-lasting response
  • Protein triggers a moderate insulin response, but causes little to no rise in blood sugar, and helps support blood sugar control
  • Fat triggers very little insulin by itself and does not raise blood sugar

This is why protein behaves more like fat than carbohydrates when it comes to blood sugar, even though it still stimulates some insulin release.

The most precise way to understand insulin signaling is this:

Rising blood sugar is the primary trigger for insulin release, while gut hormones called incretins, such as glucagon-like peptide-1 (GLP-1), amplify that response ².

The Role of Incretins and Glucagon-Like Peptide-1

When food passes through the gut, hormones called incretins are released. These hormones are made of small protein chains called peptides, and help signal the pancreas to release insulin. One of the most important incretin hormones is glucagon-like peptide-1 (GLP-1) ².

Researchers have shown that when glucose is delivered directly into the bloodstream through an intravenous infusion, the body releases less insulin than when the same amount of glucose is eaten. This difference is known as the incretin effect².

In simple terms:

• • Blood sugar turns insulin on
  • GLP-1 turns the signal up

Why Insulin Matters for Fat Loss

Insulin helps move sugar from the blood into cells so it can be used for energy or stored. While insulin is elevated, fat burning slows down⁴.

When insulin levels fall:

• • Fat burning can resume
  • Stored body fat can be released

Insulin itself is not harmful. What matters is how long it stays elevated and the environment it is working in.

[Click to learn more about the 8-Week Fat Loss Challenge]

Why Fat Changes the Post-Meal Environment

Fat does not raise blood sugar on its own. However, when fat is eaten with carbohydrates, it changes how the body responds after the meal.

Fat slows digestion, which can keep insulin elevated longer and delay the return to fat burning⁴.

More importantly, not all fats behave the same way.

The quality of fat, especially how close it is to its natural form, strongly influences whether the body enters an inflammatory or anti-inflammatory environment after eating ¹ ⁴.

Two Post-Meal Environments

Anti-Inflammatory Environment

More likely when carbohydrates are paired with fats that are:

• • Rich in monounsaturated fatty acids
  • Rich in omega-3 fatty acids
  • Found in foods closest to nature¹ ⁴

Examples:

• • Carbohydrates with avocado
  • Salmon with rice
  • Potatoes with extra virgin olive oil

Inflammatory Environment

More likely when carbohydrates are paired with fats that are:

• • Highly processed
  • Rich in omega-6 seed oils
  • Found in ultra-processed foods ⁴

Examples:

• • Pizza
  • Pastries
  • Bagels with cream cheese
  • Cheeseburgers made with processed cheese and refined oils

What Human Research Shows: The Burger with Avocado Study

Human research clearly shows that fat quality changes the body’s response after a meal.

In a controlled crossover study published in The Journal of Nutrition in 2012, researchers compared the effects of eating a hamburger alone versus the same hamburger eaten with fresh Hass avocado¹.

When participants ate the hamburger alone:

• • Inflammatory markers increased
  • Blood vessel function worsened

When avocado was added:

• • Inflammatory markers did not increase
  • Blood vessel function was preserved¹

This occurred even though the avocado meal contained more fat and more calories. The difference was the type of fat.

Avocado, rich in monounsaturated fat and natural antioxidants, shifted the post-meal response toward a less inflammatory, more protective environment¹.

How Different Meal Types Affect the Body 

Fat loss is less about eliminating foods and more about choosing combinations that keep the body out of an inflammatory environment as often as possible.

Good, Better, Best: Food Pairing for Fat Loss

Good
Carbohydrates + processed fats
→ Promotes inflammation and fat storage⁴

Better
Carbohydrates + protein
→ More stable insulin response²

Best
Carbohydrates + small amounts of natural fats
→ Supports an anti-inflammatory environment¹

A Simple Portion Guide

• • When eating carbohydrates, aim for about one thumb-sized portion of fat
  • When eating mostly protein, moderate fat is appropriate

Avoid stacking large amounts of fat onto carbohydrate-heavy meals, even when fats are healthy ⁴.

Why Breast Milk Helps Explain This

Breast milk provides a useful biological example.

By energy contribution:

• • 45–50% fat
  • 40–45% carbohydrates
  • 7–10% protein³

Breast milk raises insulin significantly without causing inflammation because the biological goal is growth and development, not fat loss³.

This reinforces a key point: insulin alone is not the problem. The environment created by food quality and food pairing matters.

The Key Takeaway

When carbohydrates are eaten:

• • Paired with omega-3 and monounsaturated fats, the body shifts toward an anti-inflammatory environment
  • Paired with seed oils and processed fats, the body shifts toward an inflammatory environment

Foods closest to nature support healthier post-meal responses and better fat-burning conditions.

Ready to Take the Next Step?

If you want to maximize fat loss, improve your health, and learn how to pair foods in a way that works with your body:

• • Consider working with a qualified coach
  • Join the 8-Week Fat Loss Challenge
  • Email questions to robert@dietfreelife.com
  • Or schedule a free consultation

Fat loss isn’t about restriction. It’s about creating the right environment, meal after meal.

References

1. 1. Fuchs, D., Erhardt, J. G., et al. (2012). Addition of avocado to a hamburger reduces postprandial inflammation and vascular dysfunction. The Journal of Nutrition, 142(6), 1028–1033.
   2. Nauck, M. A., Homberger, E., Siegel, E. G., et al. (1986). Incretin effects of increasing glucose loads in humans. Journal of Clinical Endocrinology & Metabolism, 63(2), 492–498.
   3. Jensen, R. G. (1999). Lipids in human milk. Lipids, 34(12), 1243–1271.
   4. Riccardi, G., Giacco, R., & Rivellese, A. A. (2004). Dietary fat, insulin sensitivity and the metabolic syndrome.

________

Robert Ferguson is a California- and Florida-based single father of two daughters, clinical nutritionist, Omega Balancing Coach™, researcher, best-selling author, speaker, podcast and television host, health advisor, NAACP Image Award Nominee, creator of the Diet Free Life methodology, and Chief Nutrition Officer for iCoura Health. He also serves on the Presidential Task Force on Obesity for the National Medical Association and the Health and Product Advisory Board for Zinzino, Inc.

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