Stress and dietary decisions are part of the brain-body connection. If left unmanaged, stress can lead to unwanted weight gain.

The negative consequences of stress on the body are well documented, while the effect of stress on the brain typically occupies a secondary or more periphery position and is discussed less often. Because stress is psychological as well as body-based, it is important to review how stress affects the brain — and subsequently dietary decisions and weight gain; if left unaddressed, the effects of stress on neurological process can lead to unwanted weight gain.

Stress, the Body, and the Brain

There are two main types of stress: acute stress and chronic stress. Acute stress is a short-term psychological or physiological reaction to a stimulus in the environment, e.g., traffic jam, tight deadline at work, or a health emergency. Chronic stress is a long-term psychological or physiological reaction to an ongoing situation, e.g., financial strain, chronic illness, or a profoundly unsatisfying relationship. Unlike acute stress which lasts for a shorter period, chronic stress endures over extended periods of time, like weeks, months, or even years.

Stress and the body. When a real or perceived threat is experienced, the fight or flight response is activated, leading to a cascade of hormonal changes. The amygdala signals the hypothalamus which in turn activates the autonomic nervous system (ANS) and signals the adrenal glands to release epinephrine into the bloodstream. Once this circuit is activated, it leads to several physiological changes, such as increases in heart rate, blood pressure, temperature, and glucose levels in the blood stream.

Stress and the brain. Following the cascade of physiological changes, the hypothalamic-pituitary-adrenocortical (HPA axis) stress response begins.¹ The HPA axis creates a three-stage chain reaction that leads to the release of cortisol, which increases energy levels and prepares one to deal with the perceived threat.² The three stages are:

1. The ANS signals the hypothalamus to release corticotrophin-releasing hormone (CRH).
2. CRH activates the anterior pituitary to release adrenocorticotropic hormone (ACTH).
3. ACTH activates the adrenal glands, specifically the adrenal cortex, to release cortisol.

When there is cortisol in one’s system, the HPA axis is meant to signal the hypothalamus to stop releasing CRH, thus terminating the stress response. However, when under intense or frequent stress, HPA dysfunction can occur.

Stress and Cortisol. Although cortisol has positive effects such as inflammation reduction, fat burning, and blood sugar stabilization, an excess of cortisol can lead to unwanted weight gain. Cortisol has been shown to stimulate hunger, particularly for empty calorie foods like sugary drinks and fatty foods. During chronic stress, cortisol has been linked with insulin resistance, immune system suppression, sleep disruption, increase blood pressure, and mood disorders.²

Stress and Dietary Decisions. In addition to altered brain chemistry, there is a decrease in blood flow and oxygen to the brain when stressed. This results in reduced cognitive functioning, poor or compromised decision making, and difficulty assessing the benefits and costs of a particular decision. Hormones again are relevant. Dysregulation in leptin, a satiety hormone, and ghrelin, a hunger hormone, are related to stress. Following stress, leptin has been found to decrease while ghrelin has been found to increase.^3,4  This dysregulation — coupled with impoverished decision making related to the brain’s response to stress — can present a challenge for individuals following a healthy diet; in this case, individuals may opt for high fat, high sugar, ultra-processed  foods that stimulate the brain’s reward system.

Stress, food, and the brain. A recent review of 281 studies⁵ found that the refined carbohydrates and fats typically found in ultra-processed foods have an addictive effect on the brain’s reward system. According to the study, “refined carbohydrates or fats evoke similar levels of extracellular dopamine in the brain striatum to those with addictive substances such as nicotine and alcohol.” When the stress response is activated, it is ultra-processed, high-fat, high-sugar foods that individuals tend to prefer because of the reward. Using non-healthy foods to feel better (dopamine) when stressed can lead to unwanted weight gain. The stronger the reward is, the stronger the habit — the dopamine reward — will be. As decision making capacity decreases under stress, and dopamine rewards unhealthy eating habits, it becomes easier to make poor food choices. Habitual behaviors take less cognitive effort.

Habitual Behavior and the Brain: Breaking the Habit of Poor Food Choices

The three elements of habit formation are the cue (or trigger), the routine, and the reward. The cue is the signal or stimulus that initiates the habit. The routine is the behavior that results from the cue. The reward is the positive reinforcement after performing the behavior. If expressed as a formula: Cue (stress) + Behavior (mindlessly eating chips) = Reward (feeling good). Over time, the brain creates associations with the routine and the reward, thus creating a habitual behavior.⁶

The orbital frontal cortex (OFC), part of the prefrontal cortex, is implicated in habit formation. The OFC assesses the reward associated with each behavior such that it determines the value of the reward and its importance, thereby influencing whether a particular behavior will reoccur. Over time, the behavior is learned via its reinforcement, thus amplifying the association between the cue, the routine, and the reward — ultimately leading to a habitual behavior. The OFC is also implicated in decision making and assessing consequences of decisions. Because decision making under stress is diminished, the OFC’s evaluation of consequences is compromised; and because the OFC is connected to the limbic system, it integrates emotional information and influences behaviors that offer an emotional reward.

How do you Disrupt Habitual Behavior?

One of the most important things to do to disrupt a habitual behavior is start paying attention to your behaviors and what precipitated them and what followed them. Give conscious thought to understanding what your reward from a particular behavior is — how does it make you feel? What are the emotions and cognitions that result?

Some tangible, actionable strategies include: (1) writing down how much you’ve eaten, noting your mood, situation and activity prior to eating; (2) adopting a mindful eating practice; and (3) recognizing cues/triggers that initiate the habit. Practicing self-compassion as you try to break old habits and using mindfulness techniques, such as R.A.I.N., could also help break non-preferred habits. R.A.I.N. is a mindfulness technique wherein individuals cultivate the capacity to:

• Recognize what is happening, e.g., identify the cue or trigger and acknowledge the urge to eat something unhealthy because you feel stressed.
• Allow the experience without judgment, e.g., allow yourself to experience the urge to eat something unhealthy and accept it without acting on it; be present with the experience.
• Investigate the experience with curiosity, e.g., ask yourself, “How do I feel now?” “What happened that led me to feel this way?” or “Why do I feel like I need eat something unhealthy?” Explore the emotions that are beneath the habit.
• Nurture the experience, e.g., practice self-compassion and self-kindness; acknowledge the habit might be difficult to break and that it is OK to have setbacks; congratulate yourself for recognizing the habit, just as you would congratulate a friend for doing something positive.

Implications for Clinical Practice

Because the known negative health consequences of acute and chronic stress are most talked about, it is important for health care professionals to consider how underlying neurochemical processes are implicated in the stress response. Educating patients on the negative body-based effects of stress and the role of the neurochemistry is warranted. Working with patients to understand the cognitive, emotional, and psychological downstream effects of stress relative to unwanted weight gain will offer patients additional information on which to act.

Source(s):

1 Regulation of the hypothalamic-pituitary-adrenocortical stress response

2 The cortisol connection: Weight Gain and stress hormones

3 Leptin as a biomarker of stress: A systematic review and meta-analysis

4 Ghrelin as a biomarker of stress: A systematic review and meta-analysis

5 Social, clinical, and policy implications of ultra-processed foods

6 The orbitofrontal cortex, amygdala, reward value, emotional, and decision-making

7 RAIN: A practice of radical compassion