Chapter 1: Understanding Insulin and Weight Management

The hormone insulin plays a critical role in the development of obesity. While reducing carbohydrate intake can significantly impact insulin levels—explaining the effectiveness of low-carb diets—it's important to note that this is not the sole factor influencing insulin secretion.

In earlier discussions, we have covered various strategies, including:

• Decreasing carbohydrate consumption
• Increasing fiber intake (which lowers net carbohydrates)
• Opting for lower glycemic index carbohydrates
• Changing the order of food consumption by prioritizing proteins and vegetables before carbohydrates

In addition to these methods, combining carbohydrates with specific foods can effectively mitigate spikes in glucose and insulin levels. Let's explore these foods and their impact on glycemic index:

• Vinegar
• Dairy products
• Olive oil and butter
• Acidic foods like lemon juice

One of the longstanding recommendations for weight loss includes incorporating vinegar (acetic acid), lemon juice (citric acid), or fermented foods (lactic acid) into meals. Recent research has underscored their ability to lessen the glucose and insulin response when consumed alongside carbohydrates, thus enhancing weight loss efforts.

A study titled "Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal in healthy subjects" illustrated that consuming bread with vinegar significantly reduced both glucose and insulin spikes compared to eating bread alone. Remarkably, the only difference was the addition of vinegar, while the carbohydrate quantity and type remained the same. Moreover, vinegar consumption led to increased feelings of fullness, which can be beneficial for those looking to lose weight. Notably, the greater the vinegar dosage, the more pronounced these positive effects.

A separate randomized trial revealed similar outcomes with lemon juice, demonstrating that adding it to bread reduced glucose availability by as much as 35%. Researchers measured the glucose released when comparing bread alone to bread with lemon juice, highlighting the advantages of acidic foods.

Why do these acidic foods provide such benefits? The prevailing theory suggests that they inhibit the activity of salivary amylases, which are enzymes responsible for breaking down starches.

Chapter 2: The Role of Acids in Carbohydrate Digestion

Vinegar or alternatives, like sourdough fermentation, can lower the glycemic index by as much as 20-50%. Starches, which are long chains of glucose, must be broken down into individual glucose molecules for digestion, a process reliant on enzymes called amylases. These enzymes are secreted in two main locations: the saliva and the pancreas (into the small intestine after stomach digestion).

Salivary amylases kick off starch digestion in the mouth; however, they become inactive in highly acidic environments (pH 3-4), such as the stomach, where the pH typically ranges from 1-2. After food passes into the small intestine, pancreatic amylases take over the digestion process.

Interestingly, while salivary amylases were thought to contribute minimally to starch hydrolysis due to the brief time starch spends in the mouth, studies indicate that they may play a more significant role than previously understood. The stomach's pH rises to about 4.5-6.7 during eating, allowing salivary amylases to remain active longer than anticipated, thus aiding in starch breakdown.

Research suggests that by the end of stomach processing, starches could already be 65-80% hydrolyzed before pancreatic amylases begin their work. When acidic foods like vinegar, fermented products, or lemon juice are consumed with carbohydrates, the gastric pH decreases, which inactivates some salivary amylase, leading to reduced glucose and insulin spikes.

Chapter 3: Dairy's Impact on Carbohydrate Intake

White rice holds a prominent place in Japanese and many Asian diets. According to Japan's Ministry of Health, the average Japanese individual consumes 161g of rice daily, accounting for 29% of their total caloric intake. Remarkably, Japan boasts the lowest obesity rates globally.

One study compared the glycemic index of white rice when consumed alone to its combination with 32 different foods often paired with rice. The research found that rice is rarely eaten alone, typically accompanied by meat and vegetable side dishes. Notably, dairy, soy, and vinegar showed significant effects.

When dairy products were consumed alongside rice, the glycemic index dropped by approximately 40%. While plain rice has a glycemic index of 100, combining it with milk reduced the GI to 59! Adding yogurt decreased the GI by around 28%, and cheese on curry rice lowered it by about 33%. Similarly, pairing milk with rice resulted in a GI reduction of about 32%.

The reason for these reductions could be attributed to the proteins (such as whey protein) and fats found in dairy, which may slow gastric emptying by increasing incretin hormones like GIP (Gastric Inhibitory Peptide). Another study examining the combination of potatoes with butter highlighted that this pairing significantly reduced both glucose and insulin levels.

The effect on GIP was striking—levels were eight times higher when potatoes were eaten with butter. GIP is an incretin hormone that slows intestinal transit time and is notably increased by dietary fats.

Chapter 4: Beans and Other Pairings

Adding soybean products to rice can also markedly alter its glycemic index, reducing it by approximately 25%. The soluble fiber found in beans is believed to slow glucose absorption, leading to a lower glycemic index. This effect is consistent across miso, natto, and ground soybeans, which are often enjoyed together in Caribbean cuisine.

Notably, consuming pickled vegetables with rice reduced the GI by about 25%, and sushi rice, which incorporates vinegar, lowered its GI from 100 to 67.

Chapter 5: The Influence of Fats

The addition of fats to carbohydrate-rich meals has also been studied. Researchers found that consuming white bread with butter, olive oil, or grapeseed oil resulted in a lower glycemic index compared to bread alone. Dietary fats can bind to amylose and amylopectin (the structures of starch), inhibiting B-amylase activity, which slows down glucose absorption.

Even small amounts of fat (as little as 5g) can lower the glycemic response. The combination of bread and butter reduced the GI by about 25%, while the overall blood glucose response (Area Under the Curve) dropped by 31%.

Despite identical carbohydrate quantities, the addition of olive oil or butter led to a decrease in both glycemic index and blood glucose response.

Conclusion: The Importance of Pairing Carbs

Avoid consuming carbohydrates in isolation—such as bread with jam, dry cereals, crackers, or cookies. Instead, combine carbs with vinegar, acidic foods, soy products, healthy fats like olive oil or butter, and dairy to significantly alter their glycemic effects. Since higher glucose levels correlate with increased insulin, which is a primary contributor to obesity, it's crucial to understand how to modify the impact of carbohydrate consumption.

Remember, it's not just the carbohydrates that influence weight gain—insulin plays a vital role. Therefore, it's essential to avoid "naked carbs" in your diet.

Dr. Jason Fung

For more insights, visit my YouTube channel, join our online community, and explore coaching programs at TheFastingMethod.com, along with my published works.