The Stress of Low Calorie Dieting

If you have ever sought advice for improving your health, you may have hear these two common recommendations – lose weight and reduce stress.  It turns out, those two aims may actually be working against you.  Despite logical thinking that reduced caloric intake should lead to weight loss, time after time, research (as well as anecdotal proof) has shown that this is not the case.

Roughly 1/3 of US adults are obese and obesity is becoming more common than malnutrition and infectious diseases worldwide.  Therefore, an increasing amount of research is being dedicated to weight loss and weight management.  While many plans and strategies result in weight loss, a common problem is that the weight returns.

The search is on for why weight regain occurs, in order to help devise plans that will lead to lasting healthy weight management.  At any given time in 2005, almost half (47%) of American adults were trying to lose weight.  One study found that anywhere from 30-64% of diet study participants not only regained weight, but that they gained back more than they had initially lost.  Previous dieting is a predictor of weight gain and unfortunately, the amount gained continues to grow with time.

To take a closer look, researchers set out to explore whether dieting causes an increase in stress and cortisol production, both of which are known to cause weight gain.  The study focused on the effects of two primary dieting behaviors, monitoring and restricting caloric intake, and their impact on psychological and biological stress.

Previous research has shown “stress can increase weight through the stress-responsive hypothalamic-pituitary-adrenocortical (HPA) pathway that affects energy metabolism.”  The prolonged reaction of the HPA allows elevated cortisol and may result in insulin resistance.  This connection may impact the success of weight loss or dieting attempts.

Dieting – restricting of eating – produces a feeling of deprivation and negative emotions.  The addition of fighting the natural hunger response has been shown to produce multiple negative emotions including “depression, anxiety, decreased self-esteem, nervousness and irritability.”  Additionally, one must monitor caloric intake.  This task can range from a minor inconvenience to a significant “hassle”.  Because this must be done multiple times a day, the repetitive negative experience can become a chronic stressor.  In multiple research studies, the physical act of fasting and starvation was associated with elevated cortisol.

This study sought to test two hypotheses:

(1) The monitoring aspect of dieting causes increases in psychological stress and cortisol;

(2) The restricting aspect of dieting causes increases in psychological stress and cortisol.

Participants for the study were females from the UCLA and University of Minnesota communities.  Researchers confirmed the women were going on a diet regardless of the study.  Researchers used self-reported stress, cortisol levels (from daily saliva collection) along with weight and body measurements to gauge participant’s responses.  Of the 115 who began the study, 99 completed the follow-ups.

Four diet conditions were defined to help ascertain if it is the monitoring, the restricting or the combination that causes stress.  Each subject was randomly assigned to one of these groups.

MONITORING & RESTRICTING – followed basic low-calorie diet.

  • 1200 kilocalories per day
  • No more than 50% carbohydrates, 30% total fat and 20% protein
  • Complete a daily food diary to monitor all intake.

 MONITORING ONLY – completed food diary only

  • No limitation on food intake

 RESTRICTING ONLY – All food provided to participants.

  • Low-calorie diet of foods that were prepared and packaged for the participants from 2 diet food companies.
  • Daily menus varied, but caloric intake was limited to 1200 calories per day with same carbohydrate/fat/protein percentages as the Monitoring & Restricting group.

 CONTROL – neither restricting nor monitoring

  • Participants were not placed on any type of limiting diet.
  • Participants did not complete a food diary or do other monitoring of their food intake.

Results of the study show that dieting does in fact have an impact on psychological and biological well-being and function.  Monitoring one’s food intake, in particular, appeared to increase perceived stress.  This may be due to repeatedly stopping to make food diary entries throughout the day.

Additionally, restricting food intake led to an increase in daily cortisol levels.  Researchers suggest this lends “support to the idea that stress may be a mechanism of diet failure…… A critical and related question is whether the cortisol increase is likely to translate into weight gain. No studies to our knowledge have examined basal cortisol and weight gain longitudinally in humans….”

Researchers noted the psychological and biological stress measures did not appear to be linked.  They offer a few explanations for this:

  1. The stress questionnaire used did not adequately assess the diet-related stress where another measure might be more accurate.
  2. The short time frame of the study was not long enough for the perceived stress to fully impact the body to raise cortisol. If the study had lasted longer, this may have changed.
  3. There are numerous examples in stress literature where the psychological and biological stress responses do not coincide. There may simply be more factors than we currently know.

Researchers conclude that this study was merely a starting point.  It showed that both monitoring and restricting diet affect the person both physically and psychologically.  Whether the stress would decrease after a period of adjustment time, whether stress markers increase if weight returned, or what is the relationship between method of weight loss and long term weight management…. are all questions that will need to be addressed in longer studies.

For now, it is known that chronic stress is associated with many negative health issues, including weight gain, heart disease, diabetes, cancer and impaired immunity.  Therefore, the impact of the stress of a strict diet should be considered, especially in those who are already in a high-risk classification.

You may be better served by lifestyle modifications, rather than a strict diet plan.  Finding ways to be more active, increasing whole foods, and avoiding overeating may be easier to maintain and therefore more beneficial long-term.

Your local chiropractor is a great source of information about developing a wellness lifestyle.  Your doctor can discuss risk factors for you and help you find realistic modifications to your diet, assist you in determining what type of exercise/activity would be best suited to your current health condition and help you set manageable goals for you and your family’s health.

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REFERENCE: Low Calorie Dieting Increases Cortisol   A. Janet Tomiyama, Ph.D., Traci Mann, Ph.D., Danielle Vinas, B.A., Jeffrey M. Hunger, B.A., Jill DeJager, MPH., RD, and Shelley E. Taylor, Ph.D.  Psychosom Med. 2010 May; 72(4): 357–364.