Population

Search terms were: healthy population or adult or child or obese or overweight or binge eating or problematic eating or disordered eating or diabetes or diabetic.

Intervention

Search terms were: mindful eating or mindfulness or mindfulness based intervention or meditation or mindfulness based cognitive behaviour therapy or mindfulness based stress reduction or acceptance based practices or mindful body scan or intuitive eating.

These search terms were also searched in combination with cognitive behaviour/behavior therapy or acceptance and commitment therapy or weight intervention or weight program.

Outcomes

Search terms were: weight or weight related eating behaviour/behavior or overeating or eating behaviour/behavior or eating pattern or dietary behaviour/behavior or dietary pattern or snacking behaviour/behavior or diet quality or energy intake or energy balance or meal frequency or external eating or self-regulation or intuitive eating or mindless eating or mindful eating or distracted eating or appetite awareness or hunger recognition or emotional eating or self-efficacy for eating behaviour/behavior or self-efficacy for healthy eating or self-confidence or wellness or well-being or quality of life.

Databases

The search was conducted using a University search engine which searched multiple databases: AMED (Alternative MEDicine), ASSIA (Applied Social Sciences Index), BioMed central, BMJ open, British Nursing Index, CINAHL (Nursing and Allied Health), Clinical Evidence, Cochrane Library, Conference Proceedings Citations Index, Ebsco, Medline, NICE, PsycARTICLES, PsycINFO, PubMed, Sage Journals Online and Science Direct.

Inclusion criteria

Included were papers consistent with the search strategy outlined above in the databases listed, and English articles published until August 2015.

Exclusion criterion

Excluded were non-English-language papers.

Coding and scoring of results

For both the intervention and observational studies, results were ‘coded’ and summarised as follows. A ‘positive’ code indicated the outcome demonstrated a beneficial effect of mindfulness (for example, decreased binge eating, weight loss, and reduced energy intake). A ‘neutral’ code indicated that there was no significant effect from the intervention. A mixed code indicated that there were some positive and neutral results. ‘Negative’ codes indicated that the measured outcome was in an opposite direction to the hypothesis.

Outcomes that were measured in three or more studies were ascribed a percentage score calculated by giving all positive codes one point, negative results were given minus one point, and neutral or mixed codes were given no score. The points were added per outcome, divided by the total number of outcomes and expressed as a percentage.

We acknowledge that this is not a conventional way of summarising the results of the studies and does not account for effect size. However, it provides an overview of findings in the wide range of papers included in the review, and gives an indication of whether or not there is consistency in the literature.

Characteristics of the intervention studies

The majority of interventions have taken place in the last 5 years. Most of the interventions in obese/overweight populations were undertaken in female populations, while studies of normal-weight populations included more men. Many of the interventions had small sample sizes of fifty or fewer subjects: fourteen of the overweight/obese studies⁽ Reference Kristeller and Hallett ^{11 ,} Reference Dalen, Smith and Shelley ^{13 ,} Reference Alberts, Mulkens and Smeets ^{24 ,} Reference Alberts, Thewissen and Raes ^{25 ,} Reference Baer, Fischer and Huss ^{27 –} Reference Boutelle, Zucker and Peterson ^{29 ,} Reference Daubenmier, Kristeller and Hecht ^{31 –} Reference Leahey, Crowther and Irwin ^{33 ,} Reference Niemeier, Leahey and Palm Reed ^{37 ,} Reference Stites, Singletary and Menasha ^{41 ,} Reference Timmerman and Brown ^{43 )}, and ten of the studies in normal-weight populations⁽ Reference Courbasson, Nishikawa and Shapira ^{45 ,} Reference Healy, Joram and Matvienko ^{47 –} Reference Hill, Masuda and Melcher ^{49 ,} Reference Jacobs, Cardaciotto and Block-Lerner ^{51 ,} Reference Kearney, Milton and Malte ^{54 ,} Reference May, Andrade and Batey ^{58 –} Reference Woolhouse, Knowles and Crafti ^{61 )}. Three of the studies in the overweight/obese populations were carried out among children⁽ Reference Boutelle, Zucker and Peterson ^{28 ,} Reference Boutelle, Zucker and Peterson ^{29 ,} Reference Soleimaninanadegani and Shahmohammadi ^{40 )}; one of these studies had a sample size of more than 300 but the results of this study were not clearly described⁽ Reference Soleimaninanadegani and Shahmohammadi ^{40 )}. The majority of the studies⁽ Reference Hendrickson and Rasmussen ^{15 )} among normal-weight populations were performed with students⁽ Reference Hendrickson and Rasmussen ^{15 ,} Reference Anderson, Schaumberg and Anderson ^{18 ,} Reference Mantzios and Wilson ^{34 ,} Reference Hamilton, Fawson and May ^{46 –} Reference Higgs and Donohoe ^{48 ,} Reference Hong, Lishner and Han ^{50 –} Reference Jordan, Wanga and Donatoni ^{53 )}.

Theoretical basis of the interventions in overweight and obese subjects

Mindfulness-based cognitive therapy/mindfulness action-based cognitive therapy, and mindful eating were the most commonly used approaches and were both used in four studies. Table 1 outlines the details of the theoretical basis of these studies.

Table 1

Theoretical basis of interventions in overweight and obese subjects (n 23)

MBCT, mindfulness-based cognitive therapy; MBSR, Mindfulness-Based Stress Reduction; MB-EAT, Mindfulness-Based Eating Awareness Training.

Theoretical basis of the interventions in normal-weight populations

Mindfulness was the most frequently cited basis in the studies among normal-weight subjects and was reported in eight papers which contained thirteen studies⁽ Reference Mantzios and Wilson ^{34 ,} Reference Hamilton, Fawson and May ^{46 ,} Reference Jacobs, Cardaciotto and Block-Lerner ^{51 ,} Reference Jordan, Wanga and Donatoni ^{53 ,} Reference Lacaille, Ly and Zacchia ^{56 –} Reference Papies, Barsalou and Custers ^{59 )}. Three papers used mindful eating⁽ Reference Hendrickson and Rasmussen ^{15 ,} Reference Higgs and Donohoe ^{48 ,} Reference Hong, Lishner and Han ^{50 )} and two intuitive eating⁽ Reference Anderson, Schaumberg and Anderson ^{18 ,} Reference Healy, Joram and Matvienko ^{47 )}. One paper which contained three studies used emotional awareness⁽ Reference Kidwell, Hasford and Hardesty ^{55 )}. Cognitive defusion⁽ Reference Jenkins and Tapper ^{52 )} and ACT were each used in one paper⁽ Reference Hill, Masuda and Melcher ^{49 )}.

Intervention length, intensity and scope

The majority of interventions (n 18) in the overweight/obese populations consisted of sustained weight-management programmes of medium to high intensity carried out for a medium length of time, i.e. 6 weeks to 4 months. Two studies lasted longer than 4 months and two were for a shorter duration with one study not detailing its intervention length. In many of these studies mindfulness was the sole focus of the intervention which often included mindful eating as a key element of the programme. An example of a mindfulness intervention is the one developed by Alberts et al. in 2012, a programme with five core components⁽ Reference Alberts, Thewissen and Raes ^{25 )}:

1. (1) Mindful eating;

2. (2) Awareness of physical sensations;

3. (3) Awareness of thoughts and feelings related to eating;

4. (4) Acceptance and non-judgement of sensations, thoughts, feelings, and body;

5. (5) Awareness and step-by-step change of daily patterns and eating habits.

In contrast, many of the interventions in normal-weight populations were single-day laboratory-based studies such as completion of food tasks, rating of pleasure in food or observed food intake after a test meal. Studies often looked only at a specific practice of mindfulness such as the body scan, or mindful eating of a raisin and were therefore lower-intensity interventions than those in obese/overweight individuals.

Summary of the tools/methods used to measure outcomes in intervention studies

The following two tools were the most frequently used to measure individuals’ mindfulness state and awareness:

1. (1) The Five Facet Mindfulness Questionnaire contained thirty-nine items⁽ Reference Baer, Fischer and Huss ^{27 )} It: (a) measures trait (rather than state) mindfulness across five subscales (observing, describing, acting with awareness, non-judging of inner experience and non-reactivity to inner experience); and (b) reports internal consistency of 0·87 (as measured by Cronbach’s α).

2. (2) The Mindfulness Awareness Attention Scale contained fifteen items⁽ Reference Brown and Ryan ^{62 )}. It: (a) measures trait or dispositional levels of mindfulness; (b) measures each item on a six-point Likert scale and measures levels of day-to-day awareness, attention and observation; (c) reports reliability of 0·82 (as measured by Cronbach’s α).

The Mindful Eating Questionnaire contained twenty-eight items⁽ Reference Framson, Kristal and Schenk ^{63 )} and was the only tool used to measure mindful eating. It: (a) assesses five domains of mindful eating (disinhibition, awareness, external cues, emotional response and distraction) on a four-point Likert scale; and (b) reports reliability of 0·7–0·9 (as measured by Cronbach’s α).

Intuitive eating, when measured, was evaluated using the Intuitive Eating Scale⁽ Reference Tylka and Kroon Van Diest ^{64 )} which contains twenty-one items. It: (a) assesses each item on a five-point Likert scale; (b) measures readiness to eat in response to internal cues to determine choice and quantity of food; eating to satisfy physical rather than emotional reasons; awareness and trust of internal cues; and (c) reports internal consistency of >0·70 (as measured by Cronbach’s α) and test–retest reliability of 0·90 (as measured by Cronbach’s α).

Tools used to measure eating-related behaviours

Eating behaviours were most frequently assessed using the Dutch Eating Behaviour Questionnaire⁽ Reference Van Strien, Frijters and Bergers ^{65 )}, the Eating Attitudes Test⁽ Reference Garner, Olmsted and Bohr ^{66 )} and the Eating Disorders Examination Questionnaire⁽ Reference Black and Wilson ^{67 )}.

The studies reviewed used thirty-two measures of eating behaviour assessing a broad range of eating behaviours, attitudes, cognitions about food and related issues. Some of these were previously validated tools, others adapted, and others developed specifically for a study.

Tools used to measure issues related to food consumption and hunger

The majority of self-report measures involved 24 h recalls which were translated into energy intakes by the investigator. The studies applying objective measures involved the investigator weighing the amount of food consumed, usually within a controlled laboratory environment. The assessment of hunger was always via self-report rating scale, either on an analogue or Likert scale. There were eleven measures of the quantity of food consumed via self-report and objectively weighed.

Summary of results from intervention studies

The results of the intervention studies are presented with results in overweight/obese populations being detailed before those in normal-weight populations. Most intervention effect was seen in binge eating, emotional eating and external eating and more emphasis is given to these interventions, alongside the weight-management interventions in overweight/obese populations. Overall, the studies in overweight/obese populations were relatively longer and more intense compared with those carried out in normal-weight populations. Many of the observational studies were short, day-long laboratory experiments, and these are briefly summarised after the intervention studies.

A summary of the results from the intervention studies is presented in Table 2. In five of the papers in normal-weight populations, multiple related studies were reported in a single paper and the results have been collated in Table 2⁽ Reference Mantzios and Wilson ^{34 ,} Reference Jordan, Wanga and Donatoni ^{53 ,} Reference Kidwell, Hasford and Hardesty ^{55 ,} Reference May, Andrade and Batey ^{58 ,} Reference Papies, Barsalou and Custers ^{59 )}.

Table 2

Summary of coded results from intervention studies using mindfulness, mindful eating and intuitive eating techniques

* Note that effect size is not accounted for in the coding of positive, negative and neutral and the code only provides an indicator of the direction of results; it is not trying to assess overall evidence. The ‘score’ in the final column is merely a convenient summary tool in situations where there have been three or more studies.

† Calculation of score. Only health outcomes with three or more studies are ‘scored’: a positive study scores +1 point; a negative study scores –1 point; a neutral study scores 0 points; a study with mixed results scores 0 points. The points are summed, divided by the number of studies and expressed as a percentage. An example for effect of mindful eating on weight in overweight/obese: 8 × 1=8/16=0·5, giving a score=50 %.

‡ Cholesterol and blood pressure.

Ten outcomes were given a percentage score as described previously. In studies that measured weight, binge eating, emotional eating, food intake (in overweight and obese populations) and food choice (in normal-weight populations) the score was 50 % or above, indicating that most of the results were positive or neutral/mixed. Only two studies had negative results related to weight gain⁽ Reference Kearney, Milton and Malte ^{54 )} and an increase of energy intake⁽ Reference Anderson, Schaumberg and Anderson ^{18 )}.

Results of physiological health outcomes

Weight-loss interventions

Of the eight studies that reported weight loss in overweight/obese populations, five of them were comprehensive mindfulness programmes⁽ Reference Dalen, Smith and Shelley ^{13 ,} Reference Kristeller, Wolever and Sheets ^{16 ,} Reference Corsica, Hood and Katterman ^{30 ,} Reference Daubenmier, Kristeller and Hecht ^{31 ,} Reference Soleimaninanadegani and Shahmohammadi ^{40 )} where mindful eating was a component of the programme, although details of the intervention were not reported in one of these studies⁽ Reference Soleimaninanadegani and Shahmohammadi ^{40 )}. The rest of these programmes taught the core elements of mindfulness such as being present in the moment and self-acceptance of the current state. The study with the greatest weight loss held group sessions for 24 weeks based on an acceptance-based behavioural intervention for weight loss; this was a pilot study, which taught key components of this approach including values, acceptance and cognitive defusion using mindfulness⁽ Reference Niemeier, Leahey and Palm Reed ^{37 )}.

Mindful eating in a restaurant setting was the sole focus of one of the eight studies⁽ Reference Timmerman and Brown ^{43 )}; the other two studies focused on the regulation of cues⁽ Reference Boutelle, Zucker and Peterson ^{28 )} and used an ACT approach where mindfulness was a core component⁽ Reference Niemeier, Leahey and Palm Reed ^{37 )}.

There was some variation between interventions but the following were key elements of the mindful eating components:

1. (1) Mindful eating was taught by a specific exercise such as the ‘mindful raisin’ exercise;

2. (2) Mindfully attending to the eating experience by noticing smell, texture and taste of the food;

3. (3) Reducing the speed of eating;

4. (4) Guided meditations that focused on awareness of hunger and satiety;

5. (5) Mediations to identify eating triggers including emotional triggers;

6. (6) Mediations to manage cravings.

An example of how these elements were delivered in a mindfulness intervention is given in Table 3 from a nine-session MB-EAT programme for binge eating⁽ Reference Kristeller, Wolever and Sheets ^{16 )}.

Table 3

Example of how elements were delivered in a mindfulness intervention from a nine-session Mindfulness-Based Eating Awareness Training (MB-EAT) programme for binge eating⁽ Reference Kristeller, Wolever and Sheets ^{16 )}

The studies that did not report weight loss or where there was no intervention effect on weight were more variable in terms of duration and intensity than the studies above. A couple of the studies had a mindfulness component as part of an education programme, with an ACT⁽ Reference Tapper, Shaw and Ilsley ^{42 )} and MB-EAT⁽ Reference Miller, Kristeller and Headings ^{36 )} basis and were similar to the studies where weight loss was observed. Other studies had a narrower focus, for example internal cues⁽ Reference Bacon, Stern and Van Loan ^{26 )}, mindful eating⁽ Reference Boutelle, Zucker and Peterson ^{29 )} and mindful breathing⁽ Reference Stites, Singletary and Menasha ^{41 )}, and tended to have shorter duration of 4–8 weeks.

Eating behaviours and food-related outcomes

A range of eating behaviours that may be associated with weight status was measured across the intervention studies including binge eating, emotional eating, external eating and cravings. Food intake and choices were also measured in some studies. A number of the studies showed that mindfulness enabled participants to become more aware of their internal states of hunger and satiety alongside the recognition of specific cues. Other studies showed that mindfulness generated more overall internal awareness, for example thoughts and feelings (which could include satiety and hunger). More generic mindfulness techniques emerged strongly in the studies. These included the body scan exercise and mindful breathing exercises. Acceptance-based exercises were used in a number of studies connected to recognition of emotions and thoughts.

Eating-related behaviours

Food intake and choice

Food intake was measured in four studies in overweight/obese populations and three of these reported a reduced energy intake, as measured by self-report via 24 h recalls or FFQ⁽ Reference Boutelle, Zucker and Peterson ^{28 ,} Reference Miller, Kristeller and Headings ^{36 ,} Reference Timmerman and Brown ^{43 )}. The first two of these studies were comprehensive education programmes while the third focused on intake at lunchtime only. One study did not find a reduction in energy intake as a result of their intervention among children and their parents⁽ Reference Boutelle, Zucker and Peterson ^{29 )}.

Food intake was measured in nine studies in normal-weight populations, with four studies reporting a reduction of food intake⁽ Reference Higgs and Donohoe ^{48 ,} Reference Jenkins and Tapper ^{52 ,} Reference Jordan, Wanga and Donatoni ^{53 ,} Reference Kidwell, Hasford and Hardesty ^{55 )}, four reporting neutral results⁽ Reference Cavanagh, Vartanian and Herman ^{44 ,} Reference Jacobs, Cardaciotto and Block-Lerner ^{51 ,} Reference Kearney, Milton and Malte ^{54 ,} Reference Marchiori and Papies ^{57 )} and one reporting negative results⁽ Reference Anderson, Schaumberg and Anderson ^{18 )}. One of these studies reported that higher levels of intuitive eating was associated with increased food intake in a permissive environment which was an unexpected finding⁽ Reference Anderson, Schaumberg and Anderson ^{18 )}. No change in food intake was seen in a study among veterans with chronic health problems⁽ Reference Kearney, Milton and Malte ^{54 )}. In contrast to the studies in overweight/obese populations, in all but one study⁽ Reference Kearney, Milton and Malte ^{54 )}, food intake was measured in short-duration, low-intensity experiments in laboratory settings using test meals or snacks rather than in a free-living situation.

These results suggest that more evidence is needed before it is possible to say if mindfulness and/or mindful eating can reduce the quantity of food consumed.

Food choice was measured in one study in overweight/obese populations which looked at lunches purchased and showed positive trend in choosing healthier meals⁽ Reference Stites, Singletary and Menasha ^{41 )}. Food was measured in five studies in normal-weight populations. Three of these studies reported positive food choices⁽ Reference Hendrickson and Rasmussen ^{15 ,} Reference Jordan, Wanga and Donatoni ^{53 ,} Reference Kidwell, Hasford and Hardesty ^{55 )} as a result of mindfulness intervention and two studies reported mixed/neutral results⁽ Reference Hong, Lishner and Han ^{50 ,} Reference Papies, Barsalou and Custers ^{59 )}. As per food intake, these were low-intensity, laboratory studies asking participants to make a snack choice, with the healthier choice being determined as positive.

Theoretical basis

Eight papers focused on intuitive eating⁽ Reference Anderson, Schaumberg and Anderson ^{18 ,} Reference Denny, Loth and Eisenberg ^{68 –} Reference Smith and Hawks ^{75 )}, five papers focused on mindfulness⁽ Reference Levin, Dalrymple and Himes ^{76 –} Reference Roberts and Danoff-Burg ^{80 )}, two papers focused on mindful eating⁽ Reference Khan and Zadeh ^{81 ,} Reference Moor, Scott and McIntosh ^{82 )} and one paper had a combined mindfulness and mindful eating approach⁽ Reference Beshara, Hutchinson and Wilson ^{83 )}.

Summary of results from observational studies

Sixteen observational studies were identified in the literature search and a summary of the associations observed are shown in the Table 4; it should be noted that some studies investigated more than one association. Many of the observational studies looked at associations between an aspect of eating or mindfulness and related it to an outcome in an existing cohort, for example level of mindfulness, or intuitive eating and BMI. Associations were made using the tools and scales already outlined in the intervention studies.

Table 4

Summary of coded results from observational studies showing the association between mindfulness, mindful eating and intuitive eating and parameters related to health measures and eating behaviours

* Note that effect size is not accounted for in the coding of positive. The code only provides an indicator of direction of results and is not trying to assess overall evidence.

Two of the cohorts were substantial, with 1000⁽ Reference Moy, Petrie and Dockendorff ^{72 )} and 2000⁽ Reference Gast, Madanat and Nielson ^{69 )} subjects, respectively. The cohort populations were diverse, with six undertaken among university students⁽ Reference Gast, Madanat and Nielson ^{69 –} Reference Herbert, Blechert and Hautzinger ^{71 ,} Reference Outland, Madanat and Rust ^{73 ,} Reference Roberts and Danoff-Burg ^{80 ,} Reference Moor, Scott and McIntosh ^{82 )} and two taken among other young adult populations⁽ Reference Denny, Loth and Eisenberg ^{68 ,} Reference Herbert, Blechert and Hautzinger ^{71 )}. The remaining cohorts were spread across a wide age spectrum from middle school⁽ Reference Moy, Petrie and Dockendorff ^{72 )} to older obese adults⁽ Reference Paolini, Burdette and Laurienti ^{78 )}. Four of the cohorts were from overweight/obese populations of which two were waiting for bariatric surgery⁽ Reference Levin, Dalrymple and Himes ^{76 ,} Reference Ouwens, Schiffer and Visser ^{77 )}.

Intuitive eating was associated with a lower BMI in four studies⁽ Reference Denny, Loth and Eisenberg ^{68 ,} Reference Hawks, Madanat and Hawks ^{70 ,} Reference Sairanen, Tolvanen and Karhunen ^{74 ,} Reference Smith and Hawks ^{75 )}. Other observations included a decreased emotional eating with higher levels of mindfulness⁽ Reference Levin, Dalrymple and Himes ^{76 ,} Reference Ouwens, Schiffer and Visser ^{77 ,} Reference Pidgeon, Lacota and Champion ^{79 )} and a higher level of everyday mindfulness was related negatively to self-report serve size of energy-dense food⁽ Reference Beshara, Hutchinson and Wilson ^{83 )}. In one of the large cohorts in young adults, there was no difference in intuitive eating by age or sex⁽ Reference Denny, Loth and Eisenberg ^{68 )} while another study which compared males and females in a young adult population found higher levels of anti-dieting and self-care subscales of the intuitive eating scale⁽ Reference Gast, Madanat and Nielson ^{69 )}. One study found males trusting their bodies more than females on when to eat⁽ Reference Denny, Loth and Eisenberg ^{68 )} but this was reversed in a second study⁽ Reference Moy, Petrie and Dockendorff ^{72 )}. Another study looking at associations with intuitive eating showed that those who consistently overrode fullness feelings were more likely to use moderate to extreme effort to maintain their weight⁽ Reference Outland, Madanat and Rust ^{73 )}.

Interoceptive sensitivity is a measure of awareness of the subject’s bodily state; this was positively related to higher levels of intuitive eating⁽ Reference Herbert, Blechert and Hautzinger ^{71 )}. An online survey in Pakistan showed a significantly positive relationship between overall mindful eating and mental well-being⁽ Reference Khan and Zadeh ^{81 )}. In one of the group of bariatric patients, greater mindfulness, particularly awareness, was related to fewer binges and emotional eating⁽ Reference Levin, Dalrymple and Himes ^{76 )}. Another observation in bariatric patients showed that mindfulness was positively associated with restrained eating behaviour⁽ Reference Ouwens, Schiffer and Visser ^{77 )}.

These studies indicate that both mindfulness and intuitive eating showed promise in positively influencing complex relationships with food and eating behaviours.

Increased awareness of, and increased responsiveness to, internal physical cues

Interoception can be measured by an individual’s ability to report their heart rate. Interoception is connected with the mindful awareness of an individual’s internal state, especially in relation to physical factors such as hunger and satiety. Increased awareness enables individuals to eat in response to these physical cues of hunger and satiety.

Mindful eating has been shown to slow down consumption of a meal and allows both registration of feelings of fullness and greater control over eating⁽ Reference Gerweck and Celentano ^{84 ,} Reference Lofgren ^{85 )}. Additionally, a slower pace of eating reduces overall energy consumption as individuals feel full on a smaller quantity of food⁽ Reference Monroe ^{86 )}.

One study using fMRI showed a decrease in mid-line cortical structures associated with interoception during a mindfulness body scan. This suggests an increased awareness of internal state⁽ Reference Ives-Deliperi, Solms and Meintjes ^{87 )}. In another study, fMRI results showed reduced activation in the insula⁽ Reference Farb, Anderson and Mayberg ^{88 )} which is the part of the cerebral cortex implicated in self-awareness and perception and hence is linked with interoceptive awareness.

Increased awareness of, and reduced responsiveness to, internal emotional cues

Mindfulness trains individuals to notice distressing thoughts, emotions and sensations. By increasing awareness of these cues, individuals are then able to tolerate their distress and not allow these non-physical cues make them eat more⁽ Reference Ouwens, Schiffer and Visser ^{77 )}.

By learning to bring the experience fully into awareness many types of distress that would have provoked an automatic reaction can be tolerated. Thus, distress tolerance is increased and automaticity reduced. In relation to emotional eating, mindfulness reduces misperception of emotions as hunger and therefore stops increased eating in response to non-physical cues⁽ Reference Ouwens, Schiffer and Visser ^{77 )}.

As defusion-reduced reactivity enhances tolerance to non-physical emotional cues, the cultivation of mindfulness becomes self-reinforcing⁽ Reference Caldwell, Baime and Wolever ^{89 )}. Further, mindfulness increases the capability to relax when faced with negative events and emotion. This has been found to be especially true in reducing impulsivity, which is associated with mindless overeating⁽ Reference Ouwens, Schiffer and Visser ^{77 )}.

fMRI studies have shown altered activity levels in the amygdala related to general emotional arousal/salience following mindfulness training. Decreased activation has been found in the amygdala, the parahippocampal area and the insula during perception of negative stimuli in subjects but these activity levels have been regulated following mindfulness training⁽ Reference Lutz, Herwig and Opialla ^{90 )}. Others have used fMRI to show that mindfulness makes an impact on the neural systems underlying emotional regulation. It appears to regulate amygdala functioning via functional connectivity from the medial prefrontal cortex⁽ Reference Murakami, Katsunuma and Oba ^{91 )}.

fMRI studies conducted on individuals practising mindfulness have found a significant reduction in activity in the anterior cingulated cortex region which plays a role in the processing of emotion. ‘Findings collectively show that mindfulness meditation has an overall “quietening” effect on brain regions associated with subjective and cognitive appraisal of emotions’⁽ Reference Ives-Deliperi, Solms and Meintjes ^{87 )}. Significant self-reported differences in awareness of emotion are unlikely to be simply due to a blunting of the emotional experience but ‘represent more fundamental change in regulatory response’⁽ Reference Farb, Anderson and Mayberg ^{88 )}.

Anatomical studies lend further support to changes in the areas of the brain associated with emotional regulation. Studies conducted pre- and post-MRI on participants following an 8-week mindfulness programme found an increase in grey matter concentration in the left hippocampus and posterior cingulated cortex, temporo-parietal junction, and cerebellum – areas associated with learning and memory processes, emotional regulation and self-referential processing⁽ Reference Hölzel, Carmody and Vangel ^{92 )}.

Increased awareness of, and reduced responsiveness to, external cues

Overeating may reflect a non-mindful reliance on environmental or external cues (for example, packaging size), so that the cues destroy the subject’s ability to self-monitor the food they eat⁽ Reference Beshara, Hutchinson and Wilson ^{83 )}. The use of mindfulness is designed to interrupt these automatic, non-conscious external influences⁽ Reference Forman and Butryn ^{93 )}. Increasing awareness of an individual’s reactions to attractive food items, and a recognition of these reactions as passing mental states rather than real experiences, reduced the likelihood of individuals initiating purchasing and eating behaviours⁽ Reference Papies, Barsalou and Custers ^{59 )}. Mindfulness practice⁽ Reference Beshara, Hutchinson and Wilson ^{83 )} and mindful eating specifically reduced the impact of the external norms around consumption and enabled individuals to reduce their food intake⁽ Reference Mantzios and Wilson ^{34 ,} Reference Wansink ^{94 )}.

fMRI has been used to compare results of subjects who received an 8-week mindfulness-based stress reduction course with those of a control group⁽ Reference Kilpatrick, Suyenobu and Smith ^{95 )}. When asked to pay attention to the external sounds in the scanner environment, the mindfulness group showed increased functional connectivity in auditory and visual networks and the areas associated with attentional and self-referential processes.

These observations from fMRI studies are of interest but are insufficient on their own to explain the mechanism by which mindfulness exerts its effects. More research is needed to fully elucidate further mechanisms and these must explain other influencing behavioural factors.