Think back to the last meal you really enjoyed. At some point, you put down your utensils and pushed away your plate. What propelled you to do that? Did you feel too full to take another bite? Or had you cleaned your plate, as you were taught to as a child?
Many psychological factors are involved in what makes people stop eating, but physiological factors are at play as well. Learning how to feel full for longer periods of time would be useful in the battle of the bulge, but is that possible? Current research suggests that including certain macronutrients in our daily diet may help us ward off hunger and lose weight in the process. Here are some real-world strategies to share with clients.
The Drive for Food
The reasons why we eat—for instance, what drives hunger and what sparks appetite—are complicated and not clearly understood. The eating process is thought to be triggered by many intricate mechanisms, such as a decrease in blood glucose levels prior to ingestion of meals; hormones that regulate digestion; the nutrient composition of the meal; the size and frequency of meal intake; and caloric density (amount of calories per weight of food). Other mechanisms include the influence of sensory factors, such as smell, taste and texture (Jéquier & Tappy 1999).
Hunger, or the physiological drive to eat, is equally complex. True hunger is not selective; any food will serve the need. Hunger pangs result from intense stomach contractions that occur when the stomach has been without food for at least 3 hours and that increase in intensity the longer the body goes without food (Insel, Turner & Ross 2002). However, many people fail to recognize the sensation associated with actual hunger pangs, and most can attest to eating when not truly hungry. One thing is certain: The current obesity epidemic is evidence that people in developed nations are overconsuming food beyond the physiological need explained by hunger (Jéquier & Tappy 1999).
If true hunger is motivated by physiological needs, appetite is the psychological drive to eat. This is where the desire or even craving for certain foods takes over, often in the absence of real hunger (Insel, Turner & Ross 2002). A range of environmental and social eating triggers influence our desire for food. Time of day, cultural preferences, social acceptance, food availability, stress and boredom are just a few of the psychological aspects that affect food intake (De Graaf et al. 2004). Eating triggers—many of which go unrecognized—initiate and influence our eating patterns throughout the day. The most readily recognized patterns are dictated by the clock; for instance, the pattern of eating lunch at noon as opposed to 3:00 pm. But even that is arbitrary, since many cultures do sit down to a hearty meal later in the day. Other triggers are dictated by societal trends or expectations. For example, just walking into a movie theater can make some people crave a bag of popcorn.
Fill ’er Up
During any meal or snack, there comes a point when enough food is consumed to suppress hunger. This is known as satiation, or what we commonly refer to as a feeling of fullness. Self-awareness of satiation is crucial, because far too many people continue to eat until their plate is empty, long after they actually feel full.
After eating, there should be little drive to eat again for a period of time. This time period until hunger recurs is termed satiety (Jéquier & Tappy 1999). Satiety, which varies greatly among individuals, is affected by internal mechanisms, such as the return of hunger, and by environmental and social eating triggers that stimulate our appetite (De Graaf et al. 2004). How else can you explain being able to eat an entire Thanksgiving dinner and still have room for a slice of pumpkin pie with whipped cream on top?
When it comes to staying full, it helps to realize that calories are not treated equally in the body. The different macronutrients (e.g., protein, carbs and fat) each have a different effect on satiety. The proposed hierarchy for macronutrient effect on satiety is protein, then carbs, then fat (Jéquier & Tappy 1999; Gerstein et al. 2004).
Protein, which contains 4 calories (kcal) per gram (g), has the strongest effect on satiety (Gerstein et al. 2004). This could be one reason why some people claim they feel full longer and lose more weight (at least initially) while on a high-protein, low-carb diet. Although the average person in the U.S. consumes adequate protein on a daily basis, many Americans get their protein from less healthy food sources, such as red meat. Choosing healthy protein sources takes a little thought and preparation, a process often overlooked by those who tend to eat on the run.
The research is a little less definitive as to the satiating affect of carbohydrates, which contain 4 kcal/g, and fat, which weighs in at 9 kcal/g. Some studies suggest that calorie for calorie, fats and carbohydrates have a similar effect on satiety when eaten in equal amounts (Rolls 1995).
That said, certain carbohydrates appear to be more effective than others in warding off hunger. Dietary fiber, a complex carbohydrate that is not completely digested by the body, has consistently demonstrated a stronger effect on satiety in comparison with other types of sugars or digestible complex carbohydrates (Gerstein et al. 2004). This is in keeping with the theory that foods that contain dietary fiber tend to have a lower glycemic index (GI). Lower-GI foods have been shown to have a less dramatic effect on insulin and blood glucose levels, promoting greater satiety, whereas higher-GI foods may actually promote hunger (Roberts 2000). Incorporating high-fiber carbohydrates is easy if you choose whole grains, fruits and vegetables and steer clear of highly refined flour products, such as processed snack foods and products made with white flour.
A common misconception is that a high-fat meal will provide fuel for the long haul. Actually, research has demonstrated that fat has the weakest effect on satiety (Gerstein et al. 2004). This is unfortunate, for two reasons: First, fat provides the highest caloric cost of the macronutrients. Second, fat is highly palatable to most people, making it very pleasing to the taste buds. Palatability and increased caloric density of a food have both been shown to influence food choice (Gerstein et al. 2004). The irony here is that even though high-fat foods don’t curb hunger very well, they tend to be overconsumed simply because they taste good. On the flip side, lower-calorie, nutrient-dense carbs, such as whole grains and vegetables, may be less palatable in terms of taste, but they provide better satiety than fats.
The Combined- Meal Concept
In the real world, most people don’t make their food choices based on food groupings or individual macronutrient preferences. It’s also important to recognize that a particular food will often contain more than one macronutrient. For example, many grain products contain carbohydrates and protein; dairy products contain protein, carbohydrates and fat; and meat products contain protein and fat.
Rather than making satiety the goal, it is better to consume a range of macronutrients at each meal in order to benefit from a variety of different nutrients.
When it comes to meal composition, a healthy approach to follow is the combined-meal concept. Using this method, each meal contains sources of carbs, protein, fat and dietary fiber to provide greater satiety and access to a wider range of macronutrients. For real-world examples of the combined-meal concept, see “Fill Up by Combining Macronutrients,” on page 87.
Rating Your Hunger
One way to make better food choices is to determine what is driving the need to eat. A great tool for this is a basic hunger scale, which lets you rate how hungry you are before eating a meal or snack and then again when you are finished. This rating system allows you to evaluate your daily eating patterns so you can learn to differentiate between actual physical hunger and mindless eating (Gaesser & Kratina 2000).
Here’s how the hunger scale works: On a scale of 1–10, users rate their hunger before and after eating. The number 1 represents starvation, the midpoint of 5 represents being neither hungry nor full, and the number 10 represents being very uncomfortable or what is known as “Thanksgiving full” (Gaesser & Kratina 2000).
Sounds easy enough to follow, right? Not if you eat out a lot. That’s because restaurants serve up excessively large portions, which can increase the amount of calories consumed. One study demonstrated that people consumed 30% more calories when offered a larger portion at lunch (Rolls, Morris & Roe 2002). Rather than giving up on restaurants entirely, there are some practical ways to buck this trend. Remember that the first bites of any meal are the most appealing, since that’s when the physical drive for hunger is strongest. The more food you eat, the more hunger is appeased; the pleasantness of the meal begins to subside as satiety takes over. Curb your portions by taking home half of your meal. And remember to ask for a take-out container or doggie bag when you order, so you can divide portions before you start eating!
Your Just Desserts
In a perfect world, we would eat only when hungry, and we’d learn to keep our appetite in check. In the real world, life challenges us with many stressors that can influence our eating. Acknowledging our eating patterns and food choices is the first step toward keeping hunger at bay. We need to learn to listen to and rely on actual bodily cues for hunger and satiety and to recognize that our food choices can make or break our day—and our long-term health!
One sure way to overeat is to go for long time periods without food. Many people (fitness professionals included!) skip meals to save calories or because they are crunched for time. Here are some helpful tips on how to get through a long day of clients and classes:
- Don’t go more than 4–6 hours between meals and snacks; allowing yourself to get overly hungry can lead to excessive consumption later in the day.
- Pack a to-go bag with healthy food choices (see examples of combined meals and snacks on page 87) to help slow your drive for food until you can consume a meal.
- Identify potential pitfalls and eating triggers throughout your day. If you have to eat a handful of raw, unsalted almonds to ward off hunger while training a client, think of it as fulfilling your duty to be a good role model!
The following meals and snacks combine macronutrients, including carbohydrates, protein, fat and dietary fiber, to promote greater
- 1/2 cup oatmeal, a piece of fruit and an 8-ounce glass of low-fat milk
- 2 slices whole-grain toast spread with 2 tablespoons (tbs) peanut butter and banana
- 1 ounce (oz) part-skim-milk mozzarella string cheese and an apple
- 3 oz lean deli meat, such as turkey breast, and 2 slices whole-grain bread
- a handful of baby carrots and 22 whole unsalted, raw almonds (1 oz)
- 1/4 cup hummus on 7 whole-grain crackers
- 8 whole-wheat tortilla chips and guacamole dip
- 6 oz low-fat yogurt and 1 cup whole-grain cereal
- 3 oz water-packed canned tuna on 1/2 whole-wheat bagel
- a handful of trail mix made with dried fruit and nuts
- a scrambled egg on a slice of whole-wheat toast
- 6 oz low-fat yogurt topped with 2 tbs wheatgerm
- 1/2 cup oatmeal, a piece of fruit and an 8-ounce glass of low-fat milk
De Graaf, C., et al. 2004. Biomarkers of satiation and satiety. American Journal of Clinical Nutrition, 79, 946–61.
Gaesser, G.A., & Kratina, K. 2000. Eating Well, Living Well: When You Can’t Diet Anymore (pp. 43–60). Parker, CO: Wheat Foods Council.
Gerstein, D.E., et al. 2004. Clarifying concepts about macronutrients’ effects on satiation and satiety. Journal of the American Dietetic Association, 104 (7), 1151–53.
Insel, P., Turner, R.E., & Ross, D. 2002. Nutrition: 2002 Update. Sudbury, MA: Jones & Bartlett Publishers.
Jéquier, E., & Tappy, L. 1999. Regulation of body weight in humans. Physiological Reviews, 79 (2), 451–80.
Roberts, S.B. 2000. High-glycemic index foods, hunger, and obesity: Is there a connection? Nutrition Reviews, 58 (6), 163–69.
Rolls, B.J. 1995. Carbohydrates, fats, and satiety. American Journal of Clinical Nutrition, 61 (Suppl.), 960S–67S.
Rolls, B.J., Morris, E.L., & Roe, L.S. 2002. Portion size of food affects energy intake in normal-weight and overweight men and women. American Journal of Clinical Nutrition, 76, 1207–13.
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