To manage our caloric energy balance, why do we eat a high protein whole food nutrient-dense diet, workout consistently, and create lifestyle changes to benefit our eating habits, rather than eating smaller portions of junk food whilst being sedentary?
To understand this, we must examine how macronutrients, physical activity, and fiber affect satiety, as well as the psychology of why we overeat.
Through this, we need to look at the physiology of several hormones that can contribute to satiety. This includes the sites of synthesis and mechanism of action that occur through major gut hormones, cholecystokinin (CKK), glucagon-like peptide 1(GLP-1), peptide YY(PYY), ghrelin, and leptin(1).
Cholecystokinin(CKK) is a hormone that is released by the small intestine that acts on the brain to reduce food intake and increase feelings of fullness(2)
Glucagon-like peptide 1(GLP-1) is a hormone that is released by the small intestine. It acts on the brain to reduce appetite and gastric emptying and helps stimulate the release of insulin(3).
Peptide YY is a hormone that is released by the small intestine acting on the brain to reduce appetite, increase the feeling of fullness, and slow the emptying of the stomach(4).
Ghrelin, often referred to as the 'hunger hormone' is produced by the stomach, and stimulates appetite(5).
Leptin is produced by the fat cells and plays a key role in regulating energy balance by reducing appetite and increasing energy expenditure(6).
Satiating Affect of Macronutrients
Macronutrients include proteins, carbohydrates, and fats and can affect satiety in different ways.
First, studies have consistently shown that protein content in a meal is a stronger determinant of satiety compared to carbohydrates or fats. For example, a meta-analysis of 24 studies found that increasing protein intake by 5-30% led to significant reductions in energy intake and body weight (7). Another study showed that participants who ate a high-protein breakfast reported feeling fuller and more satisfied throughout the day and consumed fewer calories at subsequent meals(8).
Protein also triggers the release of hormones cholecystokinin(CKK)(2), Peptide YY(4), and glucagon-like peptide 1(GLP-1)(3). Furthermore, protein increases leptin levels(15) and suppresses ghrelin secretion more effectively(9). Thus, regulating appetite and promoting the feeling of fullness and satisfaction after a meal.
Next, the type of carbohydrates can affect satiety. High-fiber, complex carbohydrates increase the feeling of fullness and satisfaction, whereas, simple carbohydrates can have the opposite effect.
For instance, one study found that when participants consumed a high-fiber, low-glycemic breakfast, they reported feeling fuller and having lower levels of hunger hormones compared to when they consumed a low-fiber, high-glycemic breakfast(10).
Although fats are generally less satiating than protein and complex carbohydrates, studies suggest that consuming moderates amount of healthy dietary fats such as those found in almonds can help slow the digestive process and promote feelings of fullness(11).
Thus, solely looking at macronutrients, eating a diet high in protein, fiber, complex carbohydrates and a moderate amount of healthy fats will help keep you more satiated.
Does physical activity create an appetite-suppressing effect?
Yes! Imagine being able to increase muscle mass, decrease fat, and suppress appetite!
Well, you can by exercising!
A study of food intake in relation to the physical work of various jobs illustrated a diagram that indicated increasing physical activity within a job improved satiety signaling(12). Furthermore, exercise influences the drive to eat through the modulation of hunger which is a conscious sensation reflecting a mental urge to eat(13). Whereas, studies show that sedentariness leads to weak satiety signaling and leads to being more susceptible to overeating(14).
Physical activity can also impact the secretion and sensitivity of satiety hormones.
Studies have shown that exercise can increase the production and sensitivity of peptide YY and glucagon-like peptide 1(16). In addition, exercise also increases leptin sensitivity(6) and decreases or interferes with the production of ghrelin(17), thus leading to an increased feeling of fullness and reduced appetite.
Does fiber affect satiety?
First, the way people eat may encourage excess energy intake as many studies have found associations between body weight and the speed of eating. The eating behavior of obese subjects ate faster than lean subjects(18). Hence, chewing foods high in dietary fiber requires more time and effort, prolonging oral exposure and allowing time for signals that mediate satiety sensations(19).
Secondly, it is worth noting that the type of fiber and the form in which it is consumed can influence the extent to which it promotes satiety. Soluble fibers, tend to form a gel-like substance when they come into contact with water, which may be more effective at promoting feelings of fullness. On the other hand, insoluble fibers tend to promote bowel regularity, speeding up food and waste through the digestive system, which contributes to the majority of stool formation. Overall, consuming a diet rich in dietary fiber promotes satiety(20).
Next, examining the physiology of fiber in relation to satiety, a research paper reviewed various scholarly sources to investigate the major gut hormones in how they responded to beta-glucan, a soluble fiber(21).
Cholecystokinin (CKK), in a dose-responsive manner, increased linearly over the increase of beta-glucan concentration(22). Similarly, glucagon-like peptide 1 significantly increased when drinking a beverage with low viscosity containing 5g soluble and 5g insoluble fiber compared to a high viscosity beverage with the same volume but with low fiber content(21). Likewise, peptide YY concentration increased in a dose-dependent manner linearly with increasing doses of beta glucagon (23). On the other hand, ghrelin decreased in response to ingesting beta glucagon-enriched bread versus a control bread(24).
For these reasons, physiologically, an increase in fiber intake in the diet increases satiety which helps in consuming fewer calories.
How much fiber should you consume?
Findings depict fiber intake offers the potential in reducing all-cause mortality rates by 10% per 10-gram increase in a day(25), On this account, we must figure out how much our bodies can tolerate before being uncomfortable.
The USDA recommends about 14g of fiber per 1000kcals and states that we can tolerate no more than 70 grams. However, this depends entirely on the individual as some may extract energy from fiber and utilize it better than others.
Psychology of Calories In
Eating is not only due to physiological responses of the body, but rather it can also occur through psychological factors like boredom, stress, lack of sleep, environmental factors, habits, or through evolutionary biological responses to dieting.
Are you eating because of hunger or boredom?
Anecdotally, we are guilty of this!
Think about a day when you were busy and a day you had nothing to do. You must have eaten more often or at the very least thought about food more on a free day.
In actuality, studies support this as 33 participants in a diary study across 7 days demonstrated that a state of boredom relates to higher consumption of fats and carbohydrates(26). Thus, pick up a new hobby, or keep yourself occupied, as being bored may lead to overeating!
Are you stressed out? This may also be the reason why you are overeating!
First, we must differentiate between short and long-term stress. Short-term stress can disrupt appetite as the nervous system sends signals to the adrenal gland to produce more epinephrine triggering a flight or fight response. As this stress persists in the longer term, an elevated release of cortisol occurs, again, through the adrenal gland. As a result, appetite, and the motivation to eat more calorie-dense food increase.
Examining the psychology of stress and eating, a study using a daily diary design in children and adolescents found that there is a correlation between stress and the desire or craving for calorie-dense food. This indicates that eating high calorie food may be a coping mechanism to regulate experienced stress(27).
In a similar manner, a study evaluated stress and emotion altering eating behavior in 59 adults. The findings emphasized the importance of individual differences but found that higher stress led to less taste eating and more hunger eating in line with various physiological stress models(28). These physiological stress models include the enhancement of ghrelin secretion and the decrease in cholecystokinin production. Hence a study determined that despite not needing the energy to replace fuel stores, food was consumed rather for a reward or coping mechanism(29).
This does not mean you should avoid stress altogether, but it does mean you may want to implement strategies that will alleviate the stress that occurs in your life. Especially stress that persists in the long term.
What are some strategies to alleviate stress?
Undoubtedly, increasing your physical activity levels and eating a nutrient dense whole food diet will relieve stress, but there are other strategies we can implement. For instance, meditating, yoga, stretching, praying, journal writing, being truthful and assertive, connecting with others, giving yourself some downtime, or simply just sleeping more can all be strategies to alleviate stress in your life!
Are you sleeping enough?
Various studies have shown that lack of sleep leads to an increase in caloric consumption, ghrelin concentration, appetite, and hunger.
In fact, a study compared randomized subjects that had usual sleep versus a sleep restriction of two-thirds of normal sleep time for 8 days. Caloric intake in the sleep-restricted group increased by 559 kcals! Essentially, sleep restriction was associated with an increase in caloric consumption without any accompanying increase in energy expenditure(30).
Moreover, another study analyzed 11 healthy adults in random order for two separate 14-day stays in a sleep laboratory. They were given either 5.5 hours or 8.5 hours of sleep. As a result, meal consumption remained similar, however, the group with restricted sleep increased consumption of calories through calorie-dense snacks(31).
In addition, a randomized, two-period study with 12 healthy men examined ghrelin levels, hunger, and appetite when given two days of sleep restriction and two days of sleep extension. Short sleep duration led to an increase in all mentioned components(32).
All in all, you got to sleep more! Ideally, 7-8 hours of sleep will lead to better utilization of peak growth hormone release, protein synthesis, muscle repair, and caloric management.
Sleeping less than 6 hours not only causes overeating but also impedes the probability of a balanced slow wave and rapid eye sleep.
What can you do to get to sleep and utilize the benefits of deep sleep (slow wave)?
First, try and follow your natural circadian rhythmicity. When waking up, get some fresh air and sunlight, boosting your wakefulness, and wait about 60-90 minutes before intaking caffeine through either coffee, tea, or pills. Next, get some exercise during the day to promote tiredness avoiding caffeine or pre-workouts if you're training in the evening. Also, avoid alcohol, nicotine, or THC in the evening, as this will hinder your ability to get into a deep sleep state. For good measure, do not take long naps close to evening, as this will interrupt your sleep-wake pattern. On top of that, avoid food intake, specifically high carbohydrate sources 2 hours prior to sleep as this will also impair your depth of deep sleep. Lastly, sleep in an environment that promotes sleep like powering off electronics, turning off lights, being in a colder temperature, and having a comfortable sleeping area.
If this does not help, talk to your physician about adding supplements like Magnesium l-threonate, l-theanine, and apigenin 60 minutes prior to sleep(33). You may also use sleeping aids like melatonin, valerian root, and lavender.
Now, let's investigate the environment in relation to overeating.
The environment around you is essential when trying to lose weight or consistently eat at a caloric maintenance or deficit. Imagine having a cupboard filled with calorie-dense processed snacks or a McDonald’s across the street.
Wouldn’t u be more susceptible to overeating?
This is proven through studies that examined the momentary food environment and cues in predicting eating behavior in overweight and obese adults. Researchers found that there was a higher likelihood of ingesting high-energy snacks when near a fast-food restaurant versus a lower likelihood when in proximity to a supermarket(34).
Similarly, cross-sectional baseline data was collected from 167 overweight and obese adolescents, and parent pairs who were assessed through 3 separate 24-hour dietary recalls. Researchers examined the relationship between an adolescent with household factors like family meal practices and food availability. They found that parents modeling healthier food practices had less high-fat food or treats at home. This ultimately led adolescents to make healthier choices, whereas, adolescents with availability to high-calorie foods were more likely to snack(35).
Correspondingly, several meta-analyses, reviews, and observational studies have highlighted lifestyle and environmental modifications to reduce the likelihood of overeating(36). As our environment becomes more obesogenic, it consequently favors behavioral choices that increase the intake of energy in excess of energy requirements(37). Due to this, creating lifestyle modifications that suppress overeating can gradually become habits that your body becomes conditioned to.
What kinds of lifestyle changes can be made in environmental settings?
As mentioned above, where you live or what is in your household can be modified to favor healthier behavior choices regarding eating. You may also change whom you surround yourself with, where you hang out or invoke some sort of restriction on your eating habits. This will create a new identity to thus adhere to long-term change. With new friends or a different space to hang out, you may abstain from making poor food choices. Also, invoking restrictions relating to macronutrients, calories, or time and picking the restriction that feels least restrictive to you will help you sustain lifestyle modifications for life!
Lastly, we will evaluate the evolutionary biological response to losing weight as weight regain has emerged as one of the most significant obstacles to obesity.
Due to our body’s comprehensive systems for restoring depleting energy reserves, you must proactively develop and implement regain prevention strategies to counter this biological influence.
This means that coaches and trainers must acknowledge and plan to maintain strategies implemented against the emerging biological metabolic influence, to thus facilitate long-term weight reduction(37).
How do you counteract biological influences?
Reducing your weight in the long term is essential! Quick weight loss strategies are not sustainable, which is one of the reasons why weight regain occurs. Create lifestyle changes that will be consistent to manage your weight for life!
Therefore...
A diet high in protein and nutrient-dense foods including fiber, working out or exercising consistently, and creating lifestyle changes to benefit eating habits will increase satiety and better the suppression of overeating.
Ask yourself when trying to consume fewer calories:
Are you taking into account your satiety levels to make it easier for you to consume less food, or facilitate changes that are sustained in the long term?
Do you consider psychological factors like boredom, stress, lack of sleep, environmental factors, habits, or evolutionary responses to overeating? How will you manage this?
Struggling to lose body fat and build lean muscle, despite your efforts? Our personalized approach offers 24/7 guidance, accountability, and unwavering motivation resulting in success that lasts for a lifetime! To learn more, click the link below.
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