Key Takeaways
  • The idea that "fat = weight gain and unhealthiness" is outdated. Lipids are a crucial energy source for the body and essential for brain function, hormone production, and the absorption of fat-soluble vitamins.
  • While the Ministry of Health, Labour and Welfare's macronutrient ratio prioritizes carbohydrates, some research suggests high-fat diets like ketogenic diets can positively impact metabolism and cognitive function.
  • Although saturated fat raises LDL, it also raises HDL, and some reports indicate it reduces dangerous small dense LDL. Therefore, it's not simply "saturated fat = heart disease."
  • Low-fat foods are often compensated with sugar and processed ingredients, which can lead to blood sugar fluctuations, reduced satiety, and a risk of fat-soluble vitamin deficiencies.
  • What's important is the "quality of fat" and the "overall balance of the diet." It's crucial to choose good quality fats (fish, nuts, olive oil, grass-fed butter, etc.) and avoid excessive intake or industrially processed oils.

Is Fat Really the "Enemy"? - Introduction

Many of us were taught that "fat is bad" when it comes to diet. We at geefee also used to favor low-fat diets, but as we've followed recent nutritional science, we've come to realize that the simple equation of "fat = bad" doesn't hold true. While excessive intake or poor-quality fats are indeed problematic, it's now understood that appropriate and good-quality fats actually contribute to maintaining health. Here, we will clearly explain the unexpected drawbacks that a low-fat approach can bring and how to properly approach fats.

Recommendations from the Ministry of Health, Labour and Welfare and Recent Research

The Ministry of Health, Labour and Welfare suggests a macronutrient ratio of 50-60% carbohydrates, 20-30% fats, and 13-20% protein. On the other hand, high-fat, low-carbohydrate diets like ketogenic diets, where fats account for the majority of total energy, are gaining attention for research showing positive effects on metabolism and cognitive function. For example, one report indicated that high-carbohydrate diets increased the risk of dementia, while high-fat diets reduced it (discussions by Dr. David Perlmutter and related research). However, national guidelines consider many factors, and a drastic, uniform change is currently difficult.

The Relationship Between Cognitive Function and Fat

You might be surprised to hear that a high-fat diet is good for the brain, but the brain is an organ rich in lipids, and cholesterol and fatty acids are crucial for the structure and signal transmission of nerve cells. Some research also suggests that midlife HDL (good cholesterol) levels may prevent cognitive decline in later years (Svensson et al., 2019). When we actually tried a diet with reduced carbohydrates and increased good quality fats, we felt less hunger and found it easier to maintain concentration. However, individual differences are significant, so please consult a doctor if you have symptoms or a history of illness.

Misconceptions About Heart Disease and Cholesterol

Saturated fatty acids tend to raise total LDL while also raising HDL and lowering triglycerides. What's important is the "type" of LDL; small, dense LDL is strongly associated with coronary artery disease. Some reports indicate that saturated fatty acids reduce this small dense LDL, so it's premature to demonize saturated fat across the board. Nevertheless, industrially processed trans fats and excessive refined vegetable oils (polyunsaturated fatty acids processed at high temperatures) should be avoided as they increase cardiovascular risk. Explanations from sources like Harvard Health also point out the importance of looking at the "quality" of fats.

Negative Impacts of Low-Fat Foods and Their Relationship with Type 2 Diabetes

Foods labeled "low-fat" often use sugar, processed starches, and additives to compensate for taste and texture. As a result, their GI tends to be high, leading to rapid post-meal blood sugar spikes, increased insulin load, and a risk of type 2 diabetes and body fat accumulation. In fact, carbohydrate-rich meals are prone to rapid blood sugar increases, while fat-centric meals tend to show smaller blood sugar fluctuations even with the same amount of calories (refer to clinical data on glycemic response). Furthermore, fat is necessary for the absorption of fat-soluble vitamins (A, D, E, K), and an extremely low-fat diet can lead to nutritional deficiencies.

Practical Advice: How to Deal with Fat

- Choose good quality fats: Prioritize blue fish, nuts, avocados, olive oil, and grass-fed butter. - Avoid processed oils and trans fats: Limit the frequency of margarine and fried foods. - Be cautious of "low-fat" processed foods: Check the ingredient list for sugar and additives. - Improve carbohydrate quality: Choose whole grains, vegetables, and low-GI foods over refined grains. - Be mindful of excessive calories: Since fats are energy-dense, managing intake is necessary. A simple trick we tried was incorporating a small amount of good quality fat into breakfast, which reduced afternoon snacking and lowered total calorie intake.

Conclusion

Fats should not be uniformly labeled as "bad." What's important is their "quality" and the "overall balance of the diet." Low-fat foods are not necessarily healthy; in fact, they can lead to blood sugar fluctuations and nutrient absorption problems due to increased sugar and processed ingredients. Instead of a blanket good-or-bad argument for saturated and unsaturated fats, it's wise to incorporate appropriate amounts of good quality fats like fish, nuts, and olive oil, and avoid processed oils and trans fats. Depending on your health status and goals (e.g., weight management, improved glucose metabolism, cognitive function maintenance), please consult a doctor or registered dietitian to find the right approach to fat intake for you. Honestly, we are still learning, but we feel that by not narrowing our dietary choices and focusing on "quality," our daily well-being has improved.

Disclaimer: The information in this article is for general informational purposes only and does not constitute medical advice. Please consult a qualified healthcare professional before making any health-related decisions.