For years, we've been told that fat is the enemy. Low-fat products lined grocery store shelves, and many of us diligently avoided butter, nuts, and other high-fat foods in the name of health. Yet despite these efforts, rates of heart disease and type 2 diabetes continued to climb. What went wrong?
The answer is simple: we were asking the wrong question. Instead of wondering "how much fat should I eat?", we should have been asking "what type of fat should I eat?" Modern nutrition science has revealed that not all fats affect your body the same way. Some fats can actually protect your heart, stabilize your blood sugar, and reduce your risk of chronic disease—while others do the opposite.
If you're living with diabetes or prediabetes, understanding the different types of fat and how they affect your metabolism is one of the most powerful tools you can have for managing your health.
Why Your Body Actually Needs Fat
Let's start by clearing up a common misconception: fat isn't just "empty calories" that make you gain weight. Dietary fat serves critical functions throughout your body:
- Energy source: Fat provides long-lasting, sustained energy that keeps you going between meals
- Nutrient absorption: Your body needs fat to absorb vitamins A, D, E, and K
- Cell structure: Every cell membrane in your body is made partly from fat
- Hormone production: Many essential hormones require fat for synthesis
- Brain health: Your brain is nearly 60% fat and relies on dietary fats to function optimally
Here's something especially important for people with diabetes: fat slows down digestion. When you eat carbohydrates alongside healthy fats, your body absorbs the glucose more gradually, leading to smaller, more manageable blood sugar spikes instead of sharp peaks and crashes.
Ironically, when people cut fat from their diets, they often replace it with refined carbohydrates and added sugars—which can worsen insulin sensitivity, raise triglycerides, and make blood sugar control more difficult.
The Four Types of Fat: A Guide for People with Diabetes
Not all fats are created equal. Let's break down the four main types and how each one affects your health:
Unsaturated Fats: Your Heart's Best Friend
Unsaturated fats are widely considered the healthiest type of dietary fat. They come in two forms:
Monounsaturated fats are found in olive oil, avocados, pecans, macadamia nuts, almonds, and peanut butter. These fats have been shown to improve cholesterol levels by lowering LDL ("bad") cholesterol while maintaining or even raising HDL ("good") cholesterol. Studies consistently link diets rich in monounsaturated fats with reduced risk of cardiovascular disease—a particularly important benefit for people with diabetes, who face elevated heart disease risk.
Polyunsaturated fats include two essential fatty acids your body cannot make on its own: omega-3s and omega-6s.
Omega-3 fatty acids deserve special attention. Found in fatty fish like salmon, sardines, and mackerel, as well as plant sources like flaxseeds, chia seeds, and walnuts, omega-3s have powerful anti-inflammatory effects. They help lower triglycerides, support healthy blood pressure, and reduce cardiovascular disease risk—all crucial for diabetes management.
Omega-6 fatty acids are found in vegetable oils, seed oils, and many processed foods. While omega-6s are essential, most people consume far too many of them relative to omega-3s, largely because seed oils (soybean, canola, sunflower, safflower) are ubiquitous in packaged foods. This imbalanced ratio can promote inflammation in the body.
The solution isn't to eliminate omega-6 fats entirely, but to reduce processed sources while increasing omega-3 intake to achieve a healthier balance.
Saturated Fats: It's Complicated
Saturated fats are found in red meat, whole-milk dairy products, butter, coconut oil, and palm oil. The relationship between saturated fat and health is more nuanced than we once thought.
While saturated fat can raise LDL cholesterol, recent research suggests it may not directly increase the risk of heart attacks or strokes as previously believed. The effect appears to depend on what saturated fat is replacing in your diet and what else you're eating alongside it.
Small amounts of saturated fat can fit into a healthy eating pattern. The problems tend to arise when saturated fats replace healthier unsaturated fats or when they're consumed as part of a diet high in refined carbohydrates and added sugars.
Because individual responses to saturated fat vary considerably, people with diabetes—especially those with existing cardiovascular concerns or a family history of heart disease—should work with their healthcare provider to determine the appropriate amount for their personal situation.
Trans Fats: The One Fat to Avoid Completely
If there's one type of fat you should eliminate from your diet, it's trans fats. Found in partially hydrogenated oils used in margarine, many baked goods, and processed snacks, trans fats are metabolically harmful in every way:
- They raise LDL ("bad") cholesterol
- They lower HDL ("good") cholesterol
- They increase triglycerides
- They significantly raise the risk of heart disease and stroke
Both the American Heart Association and the U.S. Dietary Guidelines recommend avoiding trans fats entirely. Check ingredient lists for "partially hydrogenated oil" and steer clear of products that contain it.
How Fat Affects Your Blood Sugar and Energy
One of the most valuable benefits of including healthy fats in your meals is their effect on blood glucose stability. Here's how it works:
When you eat carbohydrates alone—say, a piece of toast or a bowl of pasta—they're digested quickly, causing a rapid rise in blood sugar. Your pancreas responds by releasing insulin to bring glucose levels back down, often resulting in an energy crash a few hours later that leaves you hungry and tired.
Add healthy fat to that same meal, and the digestion process slows down. The carbohydrates are absorbed more gradually, leading to a gentler, more sustained rise in blood glucose. Your energy remains steadier, you feel satisfied longer, and you avoid the spike-and-crash cycle that makes diabetes management so challenging.
This is why meals that combine healthy fats, protein, and fiber-rich carbohydrates are the gold standard for blood sugar control. They work together to provide sustained energy and minimize glucose fluctuations throughout the day.
Simple Ways to Include More Healthy Fats in Your Diet
Adding more beneficial fats to your eating pattern doesn't require complicated recipes or expensive ingredients. Here are practical, everyday swaps you can start making today:
Cook with better oils: Replace butter or margarine with olive oil or avocado oil for cooking and salad dressings
Add seeds to meals: Sprinkle ground flaxseed or chia seeds on yogurt, oatmeal, salads, or smoothies
Eat fatty fish regularly: Aim for two servings per week of salmon, sardines, mackerel, or herring
Snack on whole nuts: Choose raw or dry-roasted nuts and nut butters with minimal added ingredients instead of processed snack foods
Include avocado: Add sliced avocado to sandwiches, salads, or eggs for a creamy source of monounsaturated fat
Read labels carefully: Avoid products containing partially hydrogenated oils, and minimize foods with seed oils listed as primary ingredients
Remember that even healthy fats are calorie-dense, so portion awareness matters. A serving of nuts is about a small handful (roughly 1 ounce), and a serving of oil is typically one tablespoon. Pay attention to your body's fullness signals rather than obsessively counting grams or calories.
Debunking Common Fat Myths
Myth #1: All high-fat diets are unhealthy. Reality: Diets rich in healthy fats from whole foods—like the Mediterranean diet—are associated with excellent health outcomes, including better diabetes management and reduced cardiovascular risk.
Myth #2: Low-fat diets are always better. Reality: Removing fat often leads to increased consumption of refined carbohydrates and added sugars, which can worsen blood sugar control and negatively affect cholesterol profiles.
Myth #3: Dietary cholesterol causes high blood cholesterol. Reality: For most people, dietary cholesterol (like that in eggs) has minimal impact on blood cholesterol levels. The types of fat you eat matter much more than the cholesterol content of foods.
Myth #4: Fish oil supplements can replace dietary sources. Reality: While supplements can be beneficial in certain situations, they shouldn't replace a balanced diet rich in whole-food sources of omega-3s and other nutrients.
The Bottom Line: Quality Over Quantity
After decades of focusing on how much fat we eat, the evidence is clear: the type of fat matters far more than the total grams on your plate.
For people living with diabetes, choosing the right fats is a powerful strategy for managing blood sugar, protecting cardiovascular health, and maintaining steady energy throughout the day. Prioritize unsaturated fats from sources like olive oil, avocados, nuts, seeds, and fatty fish. Include moderate amounts of saturated fat from whole-food sources if appropriate for your individual health status. And avoid trans fats entirely.
By replacing processed, unhealthy fats with whole-food sources of beneficial fats, you're not just improving your cholesterol numbers—you're investing in your long-term metabolic health, reducing inflammation, and giving your body the tools it needs to function optimally.
The old low-fat paradigm failed because it oversimplified a complex truth: fat isn't the villain. Used wisely, it's one of your greatest allies in diabetes management and overall health.
References
Forouhi, N. G., Krauss, R. M., Taubes, G., & Willett, W. (2018). Dietary fat and cardiometabolic health: evidence, controversies, and consensus for guidance. BMJ, 361, k2139. https://doi.org/10.1136/bmj.k2139
Sacks, F. M., Lichtenstein, A. H., Wu, J. H. Y., Appel, L. J., Creager, M. A., Kris-Etherton, P. M., ... & Van Horn, L. V. (2017). Dietary fats and cardiovascular disease: a presidential advisory from the American Heart Association. Circulation, 136(3), e1-e23. https://doi.org/10.1161/CIR.0000000000000510
