When you eat food, these neurons are in constant communication with your brain to make minute-by-minute decisions about when to start eating, when to slow down, and when to stop eating altogether. Nerves in your stomach and small intestine secrete serotonin, which not only makes you feel happy but also propels partially digested food through your small intestine and tells your stomach to wait before releasing more food downstream. Think of serotonin as a traffic light that constantly switches from green to red in order to control how and when your stomach empties.
One of the most important components in your food that tells your brain when to slow or completely shut off your hunger signal is known as bulk. Bulk is a term given to the combination of water and fiber, which occupies space in your digestive system and mechanically stretches your stomach, your small intestine, and your large intestine. Scientists believe that because bulk is the most effective satiety signal, the amount of bulk in your food is the most important determinant of how satisfied you feel after a meal.
Not only does bulk stretch your stomach and small intestine in the upper part of your digestive system, but scientists have also discovered something fascinating about the way that fiber interacts with your large intestine and brain.
When you eat fiber-rich foods, bacteria in your microbiome ferment it into short-chain fatty acids, as we discussed in chapters 5 and 7.
Not only do these short-chain fatty acids boost immune function, fight infections, improve insulin signaling, and promote insulin sensitivity, they also communicate with your brain to control how much food you eat.
What’s amazing is that your digestive system can talk to your brain using a combination of electrical signals from nerves, hormones manufactured by your digestive organs, and short-chain fatty acids created in your large intestine as a result of eating fiber.
Many people who eat a low-carbohydrate or ketogenic diet that is low in fiber find themselves quite hungry.
It can be hard to predict how eating a low-fiber diet will affect your appetite, but a growing body of research shows that diets low in fiber can interrupt the communication between your digestive system and your brain, resulting in a larger appetite and weight gain.
Perhaps you’ve experienced the sensation of feeling constantly hungry no matter how much food you eat.
If so, you may be in this subset of the population.
Researchers have found that adding fiber-rich foods to your meals and significantly increasing your total fiber intake can make a dramatic difference in how full you (and your gut bacteria) feel at all times.
In contrast to those mentioned above, there are many people who report that eating a low-carbohydrate diet actually suppresses their appetite. Many people who adopt a low-carbohydrate or ketogenic diet find that they are less hungry than before, and as a result, they eat fewer total calories, which can promote rapid weight loss.
Drinking water before a meal does not have the same effect on satiety as eating foods with a high water content. Eating foods that come prepackaged with water and fiber together is your ticket to feeling well fed. The good news is that all green light foods contain both fiber and water, so you don’t have to worry about drinking extra water to get a bulking effect. For a table of the water content of select plant foods, refer to chapter 6.
Although this concept may be challenging at first, understanding how bulk affects your digestive system and brain is actually quite straightforward. The following images illustrate the dramatic weight difference between foods that are low and high on the calorie density scale. As you read the comparisons below, ask yourself a simple question: Which foods do you think will leave you feeling more satisfied?
Olive Oil vs. Hearty Sweet Potato and Squash Soup
In this comparison, 3.5 tablespoons of olive oil have an equivalent number of calories as one serving of Hearty Sweet Potato and Squash Soup (see chapter 15 for the soup recipe). The olive oil has zero water and zero fiber, whereas the soup has 23 grams of fiber per serving and a high water content. Even though these foods have an equal calorie value, the soup is much more likely to keep you satiated than is a small amount of olive oil.
Both of the Foods Below Contain About 420 Calories
Oreos vs. Cantaloupe
Which do you think will leave you feeling more satiated, two Oreos or two cups of cubed cantaloupe? Both contain approximately 110 calories. Very few people will feel full from eating only two Oreos, so if you chose the cantaloupe, then you’re correct. In this case, both foods are low in fat, but the cantaloupe is considerably more satiating than the Oreos and contains more water and fiber than the equivalent calories in Oreos.
Both of the Foods Below Contain About 110 Calories
Peanut Butter vs. Baked Potatoes
Do you think you’d feel more satisfied eating three tablespoons of peanut butter or one large baked potato?
Both contain approximately 110 calories.
Peanut butter is more calorie dense and has much less water content in an equal calorie comparison, as shown below.
The baked potato contains 224 grams of water and 6.5 grams of fiber, whereas the peanut butter has less than 1 gram of water and 2.5 grams of fiber.
Both are nutrient dense, although the baked potato will allow you to eat a larger volume of food, feel satisfied, and optimize your insulin sensitivity simultaneously.
Both of the Foods Below Contain About 110 Calories
Dried Apricots vs. Whole Apricots
Which do you think would keep you feeling more full—½ cup of dried apricots or nine whole apricots?
Both contain approximately 150 calories.
Dried apricots and whole apricots both originate from apricots; the only difference is that dried apricots contain substantially less water than their whole counterparts.
Dried fruits are a common afternoon snack for many people who want to stay full between lunch and dinner.
But eating the equivalent calories in whole apricots will actually keep you fuller for a longer period of time because the increased water content occupies more space in your digestive system, sending a stronger signal to your brain to stop eating.
Both of the Foods Below Contain About 150 Calories
Constructing the Perfect Lunch
For best results, choose a few calorie-dense green light ingredients as the foundation of your lunch, then add a few less calorie-dense non-starchy vegetables for flavor and texture. Excellent choices for calorie-dense foods at lunch include:
Fruits: plantains, bananas, persimmons, figs, papaya, or mangoes
Starchy vegetables: potatoes, sweet potatoes, butternut squash, yams, or corn
Legumes: any variety of beans, lentils, or peas
Intact whole grains: brown rice, quinoa, millet, amaranth, farro, or barley
Minimally processed pasta alternatives: pasta made with chickpeas, quinoa, black beans, mung beans, brown rice, or lentils
The great news is that almost any recipe that you enjoyed eating for lunch in the past can be re-created with primarily green light foods, including sandwiches, burgers, tacos, stews, sushi, lasagna, and even ice cream. For examples of some of our favorite lunch makeovers, refer to chapter 15. You can also find more recipes on our website by visiting www.masteringdiabetes.org/recipes .
How to Construct No-Recipe Lunch Meals
While we have a large collection of time-tested, appetite-approved recipes at your disposal in chapter 15, we’ve also worked hard to perfect the art of the no-recipe meal.
These meals may seem overly simplistic at first, but constructing a meal without the use of a recipe is something that will save you large amounts of time in the future because it simplifies the process of preparing food while also keeping you insulin sensitive.
For a combined total of more than twenty-nine years, no-recipe meals have been our midday meal go-tos—because they’re satisfying, delicious, and very energizing.
We have also received feedback from thousands of people online saying that they love no-recipe meals because they’re efficient and require almost no thought to execute.
The first step is to ask yourself, “ Am I in the mood for sweet or savory? ” If you want to go with a fruit-based meal, choose 2 to 5 fruits, peel them as needed, and add them to a bowl. Feel free to include leafy greens like lettuce, arugula, or spinach because they slow the absorption of glucose and can help keep your post-meal blood glucose well controlled. Grab a fork and dig in, or if you’re feeling extra fancy, add spices like cinnamon, cardamom, carob powder, or cloves to take the flavor of your fruit bowl to the next level.
If you prefer a savory meal at lunch, then first choose a calorie-dense option as the base, including potatoes (any type or color), squash (any variety), yams, corn, beans (all varieties), lentils (all varieties), green peas, or intact whole grains like rice (all varieties), quinoa, or millet. Next, garnish your base with less calorie-dense vegetables such as artichokes, cauliflower, onions, mushrooms, eggplants, tomatoes, okra, asparagus, cucumber, zucchini, radishes, jicama, mushrooms, cauliflower, broccoli, or beets. Again, if you’re feeling fancy, add savory spices or herbs like cumin, paprika, curry powder, black pepper, red pepper, thyme, oregano, or sage to flavor the dish just the way you like.
Minimally Processed Pasta Alternatives
As you know by now, we are big fans of eating intact whole grains instead of refined grains. Intact whole grains are significantly better for your overall health because they are nutrient-dense and contain valuable vitamins, minerals, fiber, antioxidants, and phytochemicals that aid in nutrient absorption and transport. And remember, the term whole grain unfortunately doesn’t actually mean much for packaged products, which is why we recommend eating minimally processed pasta alternatives instead.
One of the primary reasons that pasta alternatives are listed as yellow light foods (as opposed to red light foods) is that when they are cooked, they absorb water, which lowers their calorie density while still delivering vitamins, minerals, fiber, water, antioxidants, and phytochemicals. Luckily, there are now many pasta alternatives in the grocery store that are made from chickpeas, quinoa, black beans, mung beans, soybeans, brown rice, and lentils. Technically speaking, they are still processed foods, but much less processed than conventional pastas made from wheat.
Dressings, Sauces, and Condiments
You can also include dressings, sauces, and condiments to add flavor to a meal made of green light foods.
Often, sauces are made using yellow light ingredients like nuts, seeds, coconut meat, and avocados, but as long as you use them sparingly, you can feel free to add these sauces to your meals.
Also, don’t forget that oil is a red light food; we strongly suggest that you avoid it completely in order to maximize your insulin sensitivity.
You can make many delicious sauce recipes without adding any oil, and once you get used to eating food without oil, sauces or dressings that do contain oil may taste overwhelmingly heavy.
Examples of condiments that we enjoy include coconut aminos, hot sauce, mustard, apple cider vinegar, balsamic vinegar, nutritional yeast, and oil-free hummus.
You may notice that processed coconut products are red light items and yet we’re recommending coconut aminos here.
That’s because this highly flavorful condiment is used in small quantities and does not contribute a large amount of fat or calories to your meal.
When it comes to sourcing condiments, you have two primary options
Make them at home with clean ingredients. Homemade condiments can last for many days in the fridge and for months in the freezer.