# Motivation and emotion/Book/2019/Stress and diet

* Multimedia presentation (3 min)

## Overview

Stress is a big issue in modern society, as we are faced with a number of external stressors, like working long hours, balancing family and work life, lack of sleep, or money[factual?]. Stress might sound harmless, however short-term stress can lead to headaches, stomach cramps, weight gain, and colds and flu, while chronic stress can increase the risk for obesity, type 2 diabetes, heart disease, depression, and anxiety, according to the National Institute of Mental Health (NIMH) (NIMH, 2017). Today we are more stressed than ever, Australian Psychological Society (2015) has reported that one third of Australians have a significant level of stress in their lives, which impacts their physical and mental health. While stress can be influenced by, as well as affect different aspects in people's life, this book chapter will be exploring the relationship between stress and diet.
* Case study
* "Samantha eats a LOT every evening after dinner. Here is what happens - after work, she comes home from a long hard day and prepares dinner for her 2 children and her husband. The children are at the table and then off and running almost before she sits down - they are teenagers, and have busy lives - homework, friends, their phones!
* Her husband is often late - so Samantha sits and eats mostly alone.  She’s tired, and she is resenting that she has done the work to get the dinner on the table, not easy after a long day of work, and no one is there to join her for more than 2-3 minutes.  She eats but doesn't enjoy it - she mainly tastes her bitterness.
* Later, she feels a lack - she wants to enjoy food! She gets out the treats…  and she eats.  She feels a stubborn refusal to dish out a serving of one of these foods - rather, she takes a container or two and parks in front of the TV, feeling that she can relax for the first time all day.  She eats until she feels better.  By the time she stops, she will have eaten a bag of chips or much of a carton of ice cream, or some of both. " (Palken, 2019)
This case study gives an example of how stress can influence someone's eating habits. In order to understand this process better and to find more effective ways of coping with stress, this book chapter explores the relationship between stress and diet. After interacting with the following material you should be able to answer these focus questions.
* Focus questions
* What is stress?
* What are biological and psychological aspects in regards to stress and eating behaviour?
* What moderates the relationship between stress and eating behaviour?
* What are positive and negative aspects in relationship between stress and diet?
* How can you deal with stress and diet effectively?

## What is stress?

* Are you stressed?
* Take this quiz, adapted from a scale developed by Peter Lovibond at the University of New South Wales, to find out how much stress is in your life. Click here.
Stress, like emotions, are brain activities that are both difficult to define and quantify (Kalat, 2016).
Kranner et al. (2010) present three distinct definitions of stress, seen in the box below. On the most basic level it can be defined as any change experienced by an individual. Expanding from this definition, a psychological perspective defines stress as the conditions in which the individual's coping abilities are exceeded by their environment, while a physiological perspective defines stress as the rate of exhaustion on the body (Seaward, 2006).
* stress is any external stimulus that causes arousal and tension to the individual
* stress is an internal mental state of arousal and tension
* stress is a physical response to demanding and damaging intrusions
Taking into account of all definitions of stress presented, they all share a common feature in that the outcome of a stress response is determined by cognitive processes in the brain (Ekman, 2016). External stimulus is defined as a stressor based on the perceived threat by the brain. The the threat to homeostasis may be perceived or real.

### Sources of stress

Stressors refer to any stimulus that signal the activation of the stress response (Elliot & Eisdorfer, 1982) and can be divided into different categories.
* Environment: Environmental factors of stress can lead one to feel overloaded with competing demands to adjust. Environmental stressors may include factors such as air pollution, crime, traffic, weather, population, crime and poor standards of living.
* Social Stressors: Social factors of stress include the act of attempting to meet the standards of the different social roles we identify with, for example a student, a parent, an employee etc. Social stressors may include deadlines for assignments, financial problems and relationship issues.
* Physiological: Physiological factors of stress refers to the situations and circumstances that affect the body. For example the onset of puberty and menopause, giving birth, ageing, poor nutrition, sleep disturbances, and lack of exercise.
* Thoughts: Cognitive factors of stress include whether we perceive a situation as positive or negative. Pessimistic thinking can lead to the onset of stress
(Glanz & Schwartz, 2008).

### Types of stress

However, stress is not always a bad thing as it serves an important function in the body (Kalat, 2016). In order to highlight the negative and positive of stress, Hans Selye introduced the term eustress and distress to provide distinctions between positive and negative stress (Rice, 1992).
Eustress: As the figure on the right shows, eustress refers to positive effects of stress on the body such as heightened awareness and increased mental alertness (Rice, 1992). Positive stressors can be receiving a promotion at work, moving into a new house, or having a child.
Distress: As summarised in above's figure, distress refers to stress that results in unpleasant and damaging effects to the body. There are two types of distress, acute and chronic, that can vary in intensity and duration. (Taylor, 2017). Acute distress may be experienced in situations such as believing you received a fail grade for your final exam only to realise shortly that your exam marks had been mistaken for another student and you in fact had passed. Chronic stress may occur in such traumatic events such as a death of a family member, where to grieving process may time an indefinite amount of time.
In further exploring the relationship between stress and diet it will be important to keep in mind what stress is, what its sources can be and what types of stress exist.
Test yourself!
What are the distinct definitions of stress?
Happy, unhappy, neutral
External, internal, physical
high, medium, low
All of the above :

## Biological and psychological aspects in regards to stress and eating behaviour

Stress is a challenge to the natural homeostasis of an organism, which may react by producing a physiological response to regain equilibrium lost by the impact of the stressor. One homeostasis that can be disrupted is the feeding behaviour, which can result in both hyperphagia and hypophagia (Yau & Potenza, 2014). A review by Torres and Nowson (2007) shows that 40% increase and 40% decrease their caloric intake when stressed, while approximately 20% of people do not change feeding behaviours during stressful periods. These varying results may relate to the specific type of stressor manipulated, duration of stress provocation, and variations in the satiety and hunger levels at the start of the study. For example, mild stressors could induce hyperphagia, while more severe stressor, hypophagia (Robbins & Fray, 1980). The following paragraphs will explore biological and psychological aspects involved in stress and eating behaviour further.

### The role of the endocrine system

According to Bouchez (2014), weight control during stress is often influenced by the endocrine system. During periods of stress the body releases a range of hormones including adrenaline, corticotropin releasing hormone (CRH) and cortisol (Tomiyama et al., 2014). This gives the body instant energy and sends the body into ‘fight-or-flight’ mode, which is telling the body to fight the danger or run from the danger, then eat and replenish energy even though there is no real danger (Bouchez, 2014). However, since stress is not usually in the form of physical danger, the hormones that have been released are not properly used, which causes them to remain in the body much longer than they are supposed to, causing increased hunger and driving people to eat much more than they may usually eat (Bouchez, 2014).

### Effects of the fight-or-flight response on eating behaviour

Furthermore, the energy food the body needs when it is in ‘fight or flight’ mode is sugar, to fuel the muscles quickly and effectively (Bouchez, 2014). This leads people to not only eat more when they are stressed, but also to choose carbohydrate and sugary food (generally considered poorer health choices). However, this can lead to a further problem, as it can result in stress of feeling uncomfortable with your weight, which can lead to weight control issues (Schvey, Puhl & Brownell, 2014). A study conducted by Schvey, Puhl and Brownell (2014) showed that women who were exposed to weight stigma and felt stressed over their current weight, were more likely to produce higher levels of cortisol which in turn made them more likely to gain weight. In addition, acute stress can cause the bodies metabolism to weaken, leading to digestive issues which can cause further long term weight gain (University of Maryland Medical Centre, 2014).

### The relationship between stress, eating, and the reward system

Exposure to acute stress during a positron emission tomography (PET) scan revealed that both stress and cortisol release through food enhanced dopamine release (Wand, 2007). While during normal conditions cognition is dominated by reflective cognition, during stress it is dampened and limbic circuitry hyper-activated, thus promoting “automatic” behaviours that bias survival including being vigilant for food cues (Yau & Potenza, 2013). The stressed brain expresses both a strong drive to eat and an impaired capacity to inhibit eating – together creating a potent formula for obesity. These findings are consistent with behavioural and clinical research indicating that stress or negative affect decreases emotional and behavioural control and increases impulsivity, which may synergistically contribute to greater engagement in alcohol and substance abuse and eating (Sinha, 2008).
Test yourself!
Stress influences our body in different ways which results in an impact on diet. What aspect do influence our diet?[Rewrite to improve clarity]
Hormones
Fight-or-flight mode
Reward system
All of the above :

## Factors moderating the relationship between stress and eating behaviour

Experiencing drive to eat in the absence of true caloric need or not wanting to eat if needed, is common but is subject to large individual differences (Yau & Potenza, 2013). This section discusses several common factors and types of stressor that may moderate the risk for stress-induced eating.

### Weight and diet-related metabolism

Weight-related metabolic changes may alter allostatic load, as studies have shown that increased weight, insulin resistance and high fat diets are associated with blunted responses to stress challenges and altered autonomic and peripheral catecholamine responses (Tyrka et al., 2012). This impaired “brake” system may in part explain the epidemic of non-homeostatic eating. Individuals with high BMIs show a stronger association between chronic stress and weight gain than those with low BMIs who experience similar degrees of stress (Block et al., 2009). Moreover, overweight and obese individuals appear sensitised to food cues, particularly after exposure to stress. A recent study found that among healthy lean participants, mean food craving and energy intake decreased in the absence of hunger in response to both rest and stress conditions (Lemmens et al., 2011). On the other hand, visceral overweight participants showed higher mean food craving and energy intake of hyperpalatable foods (e.g., desserts, snacks) in the absence of hunger when under stress versus rest, potentially as a mechanism to regulate and suppress stress (Lemmens et al., 2011).

### Emotional eating

As explained before, chronic stress is often accompanied by anxiety, depression, anger, and apathy (Cohen, 2000). Stressful stimuli activate the emotional nervous system and given the (above explained) rewarding properties of food, some people use hyperpalatable foods as "comfort food" as a form of self-medication to stress. A study by Garg, Wansink, and Inman (2007) showed that individuals in negative affective states don't only eat more than during happy states, but also consume more hedonically rewarding foods high in sugar and fat than happy participants.

### Restrained eating

Restrained eating refers to the voluntary cognitive control effort to restrict food intake typically for the purpose of weight loss or maintenance (Wardle, 2000). Cognitive restraint has been related to food intake under stress, with highly restrained eaters increasing and unrestrained eaters decreasing their food intake during stressful conditions (Wardle, 2000). A recent large-scale study reported that stress was related to various indices of increased drive to eat, including disinhibited eating, binge eating, and more frequent intake of hyperpalatable food (Groesz et al., 2012). While flexible restraint may be effective in weight management and prevention of excessive consumption of palatable non-nutritious food, rigid restraint may lead to sensitisation of such foods. People who maintain rigid rules around their food appear less attentive to the physiological cues of hunger and satiety, leading to overeating after a preload (Wardle, 2000).

### Sleep deprivation

Sleep deprivation is a common chronic stressor that may contribute to increased risk for obesity and metabolic diseases (Eckel, Grundy, and Zimmet, 2005). Two recent meta-analyses have found that short sleep duration (<5h per night for adults, <10h per night for children) significantly predicted obesity (Chen, Beydoun, and Wang, 2008; Cappuccio et al., 2008). More research assessing the relationship between habitual insufficient sleep and food intake is needed.

## Positives and negatives in the relationship between stress and diet

So far we have explored the relationship between stress and diet and have learned a lot about how stress can impact on someone's diet, but also how that can differ between individuals based on moderating factors like weight, emotional eating, restrained eating, and amount of sleep. Below you can find a table comparing positive and negative aspects in relationship of stress and diet.
Comparing positive and negative aspects in the relationship between stress and diet :
| Positive aspects: | Negative aspects |
| Stress can be useful in facilitating healthy eating habits (Gallant et al., 2013) | Most often associated as having a negative effect on weight control, either producing weight gain or unhealthy weight loss (Kim et al., 2014) |
| It is healthy to experience different levels of stress through life (Boulos, Tufts, & Friedman, 2014) | Stress can be influenced by and/or lead to weight, emotional eating, restrained eating, and sleep deprivation (Yau & Potenza, 2013). |
| Individuals with the skills to properly manage stress in their lives are then able to control and manipulate stress levels in order to use mild levels of stress to motivate them to lead a healthy lifestyle (University of Maryland Medical Centre, 2014) | |
* Video explaining the impact of stress on appetite
* Watch Susan Albers, Psy.D., giving some tips on how we can manage our relationship with food in stressful times to avoid ‘stress-eating. Click here.
Test yourself!
What is not a positive aspect in the relationship between stress and diet?
Stress can facilitate healthy eating habits.
Stress is always healthy.
It is healthy to experience some stress in life. :

## How to deal with stress in relationship to diet effectively

Stress is an uncomfortable feeling, which can lead people to having difficulty controlling their weight. However, there are several different coping mechanisms that can be used to reduce stress and encourage better weight control. They are:
* Exercise regularly: exercise not only helps reduce stress as it produces endorphins which produce happiness, but also supports healthy weight control (Victorian Government, 2013)
* Healthy sleep routine: a healthy sleep routine can help manage mental stress, as well as discourage emotional eating and abnormal eating patterns (Yoshikawa, Tanaka, Ishii & Watanabe, 2014).
* Eat healthy: eating a healthy, balanced diet has been shown to reduce stress and automatically helps a person control their weight.
* Know stress triggers: if a person is aware about what triggers them to feel stressed, they can aim to avoid or reduce contact with whatever is triggering stress (Victorian Government, 2012).
* Meditation: meditation exercises have been found to relax people and significantly reduce stress, and have been shown to encourage weight control by reducing people’s stress (Van Dam, Hobkirk, Sheppard, Aviles-Andrews & Earleywine, 2013).
Food to eat when stressed :
| Food | Reason to eat it |
| Dark chocolate | Is rich in antioxidants, which can lower level of stress hormones in body (Martin et al., 2009). |
| Whole-grain carbohydrates | Complex carbs can increase level of serotonin, as they digest slowly and keep blood sugar levels even (Naidoo, 2019). E.g. Sweet potato, quinoa, brown rice, oats. |
| Bananas | Contains the mood-boosting chemical dopamine, along with magnesium, levels of which plummet during stressful times and are a rich source of vitamin B6, which helps the nervous system run correctly, and can decrease stress and fatigue. |
| Fatty fish | Heart-healthy omega-3 fatty acids can help ease depression. E.g. tuna, salmon, sardines. |
| Water | Even mild dehydration can increase cortisol levels, which contributes to increased stress (McGregor et al., 1999). |
| Nuts | Satiating, help lower blood pressure, their B vitamins have been shown to help lower stress levels. |
| Oranges | Vitamin C decreases cortisol and overall stress level. |
| Avocados | Vitamins C and B6 can help reduce stress, and the fruit’s potassium may help lower blood pressure. |
(Kennedy, 2019)
* Case study
* Some suggestions for Samantha:
* 1. Set some dinner rules with children:
* E.g., Helping each other to get the dinner on the table, eating together for at least 15 minutes, and cleaning up together. If needed set a timer for those 15 minutes!
* 2. Focusing attention on food:
* Focusing attention on the food on her dinner plate. Make a point of noticing how each food looks, smells, and tastes, and trying to savour it. Eating slowly, and stop often. Putting down the fork, and talk to children.
* 3. Becoming aware of moment:
* If a snack or dessert wanted later, honour that feeling, and decide upon one food item. Dishing out one serving, according to the package serving size information, and putting the container away before starting to eat. Notice and appreciate the snack, and pay attention to all of its qualities.
Test yourself!
What food reduces stress?
Avocados
Water
Oranges
All of the above :

## Conclusion

It is very important to be aware what stress is and how it is in relationship with diet, as stress becomes a bigger and bigger issue in today's society. Stress is not only an external stimulus and internal state, but also a physical response to demanding intrusions, one of them being diet. In exploring biological and psychological aspects in regards to stress and diet the reader became aware that stress as well as diet influence each other both ways. This means stress can have an impact on the endocrine system, fight-or-flight response, and the reward system, but moderating factors like weight, emotional eating, restrained eating, and sleep deprivation have also an impact on the relationship.
As the relationship between stress and diet goes both ways as well as can be influenced by the described different factors, its dynamic can differ between individuals. However there are strategies that can be used to deal with stress effectively, including tips about what food reduces/ prevents stress.
Future research could look into more complex dynamics of stress and diet, as well as more specific aspects and specific tips on prevention.
* Take-home message
* The relationship between stress and diet is a complex interaction, which is influenced by a number of aspects that can differ between individuals. Techniques to stress reduction, as well as a healthy diet will help you stay mentally and physically healthy and improve your well-being.