Adherence to Hunger Training Using Blood Glucose Monitoring
Recruitment took place on July 2, 2014 by sending an invitation email to staff and students at the University of Otago in Dunedin, New Zealand. All participants were recruited in a single day. The pilot study took place from July 8 to Aug 6, 2014 and 30 participants were recruited. One participant discontinued hunger training due to fasting glucose levels being above the cut-off for possible diabetes diagnosis (>7 mmol/L), resulting in 29 participants being included in the final analysis.
The participants were predominantly well-educated, white women, with an average BMI of 31 kg/m (Table 1). As there were no significant differences in demographic characteristics at baseline between cohorts A and B (data not shown), only the combined results are presented.
Adherence was measured in terms of overall study retention, glucose measurement prior to eating, and compliance to the blood glucose cut-off. There was no difference in any adherence measures between lean and overweight participants (data not shown). Retention was high, with 28 out of 29 participants (97 %) completing the pilot study, well above our predetermined criterion for determining success of 85 %.
In terms of adherence to the blood testing protocol, the within-person proportion for measuring blood glucose before eating was 94 % (95 % CI 91, 98) of eating occasions, with no significant difference between cohorts A and B. This level of adherence considerably exceeded our a priori requirement of measuring before 80 % of eating occasions.
Adherence to Eating With Protocol A. Participants following protocol A, which used a universal blood glucose cut-off of 4.7 mmol/L, adhered to the goal of eating only when blood glucose was below this level 66 % of the time, which was below our within-person adherence requirement of 75 % (Table 2). Furthermore, four out of the nineteen (21 %) participants in this cohort adhered to protocol A on less than half of their eating occasions (Fig. 3), with one participant only adhering on two eating occasions over the two week period (5 % of all eating occasions).
(Enlarge Image)
Figure 3.
Histogram of adherence to eating below the blood glucose cut-off in cohort A and cohort B
Of these 19 participants, six who appeared to be struggling with only eating when their blood glucose was 4.7 mmol/L or less during the first week of training wore a continuous glucose measurement sensor during week two. On average, their blood glucose was above the protocol A cut-off of 4.7 mmol/L 85 % of the time over the seven days, or 143 hours of the total 168 hours captured. Additionally, five of these six participants had at least one day where their blood glucose never dropped below 4.7 mmol/L. Fig. 4 illustrates the results from one of these participants, showing their blood glucose over 7 days and the amount of time it was under both protocol A (universal 4.7 mmol/L cutoff) and protocol B (individualised cut-off of 6.2 mmol/L for this participant).
(Enlarge Image)
Figure 4.
Results from the continuous glucose monitoring sensor from a participant over 7 days, comparing the amount and percentage of time the participant was below the protocol A cut-off of 4.7 mmol/L and protocol B individualised cut-off of 6.2 mmol/L
A priori we decided that the blood glucose cut-off would be deemed feasible if the within-person proportion of measured blood glucose was below the cut-off on more than 75 % of eating occasions. As protocol A was below this requirement, we switched to protocol B for the remaining ten participants. For protocol B participants, their individualised blood glucose cut-off was calculated from the average of fasting glucose over the first two days of hunger training, which resulted in an average cut-off of 5.5 mmol/L (SD 3.0). The use of this individualised protocol increased adherence to the eating protocol to a within-person proportion of 84 % of the time, which was a significant increase over protocol A (p = 0.010) and met our benchmark for feasibility.
We examined whether the average of the first two days of fasting glucose was a suitable estimate of the average fasting glucose throughout the two-week period, and therefore was suitable to determine the individualised cut-off. Fasting glucose means were comparable (difference 0.07 mmol/L), with no significant difference between these time periods (p = 0.415).
A significant, albeit modest, inverse within-person correlation was observed between perceived hunger and blood glucose concentrations of r = −0.23 (95 % CI −0.15, −0.31), p < 0.001. Cohort B tended to have a stronger correlation between hunger and glucose (r = −0.33 for cohort B vs r = −0.18 for cohort A) although our small numbers probably preclude statistical significance (p = 0.082).
Overweight participants following both protocols achieved significant weight loss over the two-week period, with an average loss of 1.5 kg (95 % CI 2.2, 0.9) and a corresponding reduction in BMI of 0.6 kg/m (95 % CI 0.3, 0.8), p < 0.001 (Table 3). By contrast, lean participants maintained their weight (p = 0.337, data not shown). Although participants following protocol B appeared to lose more weight than those in protocol A, differences were not significant (Table 3).
The major themes that emerged from the exit interviews were: awareness of non-hungry eating, change of dietary intake, and the use of blood glucose monitoring.
Awareness of Non-hungry Eating. Participants reflected that hunger training made them realise that they were used to eating for reasons other than hunger, including as a way to stave off boredom, to cope with emotions, and because of habit:
Change of Dietary Intake. Most participants reduced or eliminated snacks:
Many participants chose better food, because they were more conscious of their food intake or because they noticed how their blood glucose reacted afterwards:
Many participants reduced their portion sizes at meals, and noted that they were surprised that they didn't need as much food as they had previously assumed, and could no longer imagine eating as much as before the pilot:
Conversely, a few participants reported that their portion sizes increased, since they were hungrier than usual because they were eating less frequently:
The use of Blood Glucose Monitoring. Many participants commented that their blood glucose was an unpredictable measure of their hunger:
However, most participants viewed measuring their blood glucose as a useful behaviour for gaining awareness of their eating habits:
Many participants commented that the pain with finger pricking reduced after the first week:
Results
Recruitment took place on July 2, 2014 by sending an invitation email to staff and students at the University of Otago in Dunedin, New Zealand. All participants were recruited in a single day. The pilot study took place from July 8 to Aug 6, 2014 and 30 participants were recruited. One participant discontinued hunger training due to fasting glucose levels being above the cut-off for possible diabetes diagnosis (>7 mmol/L), resulting in 29 participants being included in the final analysis.
The participants were predominantly well-educated, white women, with an average BMI of 31 kg/m (Table 1). As there were no significant differences in demographic characteristics at baseline between cohorts A and B (data not shown), only the combined results are presented.
Adherence
Adherence was measured in terms of overall study retention, glucose measurement prior to eating, and compliance to the blood glucose cut-off. There was no difference in any adherence measures between lean and overweight participants (data not shown). Retention was high, with 28 out of 29 participants (97 %) completing the pilot study, well above our predetermined criterion for determining success of 85 %.
In terms of adherence to the blood testing protocol, the within-person proportion for measuring blood glucose before eating was 94 % (95 % CI 91, 98) of eating occasions, with no significant difference between cohorts A and B. This level of adherence considerably exceeded our a priori requirement of measuring before 80 % of eating occasions.
Adherence to Eating With Protocol A. Participants following protocol A, which used a universal blood glucose cut-off of 4.7 mmol/L, adhered to the goal of eating only when blood glucose was below this level 66 % of the time, which was below our within-person adherence requirement of 75 % (Table 2). Furthermore, four out of the nineteen (21 %) participants in this cohort adhered to protocol A on less than half of their eating occasions (Fig. 3), with one participant only adhering on two eating occasions over the two week period (5 % of all eating occasions).
(Enlarge Image)
Figure 3.
Histogram of adherence to eating below the blood glucose cut-off in cohort A and cohort B
Of these 19 participants, six who appeared to be struggling with only eating when their blood glucose was 4.7 mmol/L or less during the first week of training wore a continuous glucose measurement sensor during week two. On average, their blood glucose was above the protocol A cut-off of 4.7 mmol/L 85 % of the time over the seven days, or 143 hours of the total 168 hours captured. Additionally, five of these six participants had at least one day where their blood glucose never dropped below 4.7 mmol/L. Fig. 4 illustrates the results from one of these participants, showing their blood glucose over 7 days and the amount of time it was under both protocol A (universal 4.7 mmol/L cutoff) and protocol B (individualised cut-off of 6.2 mmol/L for this participant).
(Enlarge Image)
Figure 4.
Results from the continuous glucose monitoring sensor from a participant over 7 days, comparing the amount and percentage of time the participant was below the protocol A cut-off of 4.7 mmol/L and protocol B individualised cut-off of 6.2 mmol/L
Adherence to Eating With Protocol B
A priori we decided that the blood glucose cut-off would be deemed feasible if the within-person proportion of measured blood glucose was below the cut-off on more than 75 % of eating occasions. As protocol A was below this requirement, we switched to protocol B for the remaining ten participants. For protocol B participants, their individualised blood glucose cut-off was calculated from the average of fasting glucose over the first two days of hunger training, which resulted in an average cut-off of 5.5 mmol/L (SD 3.0). The use of this individualised protocol increased adherence to the eating protocol to a within-person proportion of 84 % of the time, which was a significant increase over protocol A (p = 0.010) and met our benchmark for feasibility.
We examined whether the average of the first two days of fasting glucose was a suitable estimate of the average fasting glucose throughout the two-week period, and therefore was suitable to determine the individualised cut-off. Fasting glucose means were comparable (difference 0.07 mmol/L), with no significant difference between these time periods (p = 0.415).
Correlation Between Hunger and Blood Glucose
A significant, albeit modest, inverse within-person correlation was observed between perceived hunger and blood glucose concentrations of r = −0.23 (95 % CI −0.15, −0.31), p < 0.001. Cohort B tended to have a stronger correlation between hunger and glucose (r = −0.33 for cohort B vs r = −0.18 for cohort A) although our small numbers probably preclude statistical significance (p = 0.082).
Weight Loss
Overweight participants following both protocols achieved significant weight loss over the two-week period, with an average loss of 1.5 kg (95 % CI 2.2, 0.9) and a corresponding reduction in BMI of 0.6 kg/m (95 % CI 0.3, 0.8), p < 0.001 (Table 3). By contrast, lean participants maintained their weight (p = 0.337, data not shown). Although participants following protocol B appeared to lose more weight than those in protocol A, differences were not significant (Table 3).
Exit Interviews
The major themes that emerged from the exit interviews were: awareness of non-hungry eating, change of dietary intake, and the use of blood glucose monitoring.
Awareness of Non-hungry Eating. Participants reflected that hunger training made them realise that they were used to eating for reasons other than hunger, including as a way to stave off boredom, to cope with emotions, and because of habit:
It certainly does make you more aware–it was a good thing to do. It cut down a lot of my night-time snacking, just cruising past and something goes in my mouth without thinking. That's my major problem, this night-time grazing.
It's well up there because it's something that I don't really pay attention to. I'm just an automatic feeder. Needing to stop and think before I put something in my mouth was really good. And I very seldom eat when I'm hungry. I'm an emotional eater: bored, tired, etc.…I really want to stop doing that.
Change of Dietary Intake. Most participants reduced or eliminated snacks:
I stopped eating morning tea–just a habit because everyone else has something to eat. But I mean, I have an office job–I'm just sitting on my bottom not burning up much energy, so now I just have coffee instead. By lunchtime now, I'm feeling hungry.
The thing I cut out was the snacking–that was the main impact. For instance I used to eat bag of chips for no reason, just because it seemed like a good idea.
Many participants chose better food, because they were more conscious of their food intake or because they noticed how their blood glucose reacted afterwards:
My lunches I've changed totally. It's now three mandarins, a pottle of yoghurt, and a banana. And before? It was anything that I wanted.
I'm not eating things like chips and crackers. Now it's a treat. It's really changed how much processed food and I'm definitely eating much more vegetables, and enjoying them. It just seems like a waste now to eat a bag of chips, since then I can't have dinner.
Many participants reduced their portion sizes at meals, and noted that they were surprised that they didn't need as much food as they had previously assumed, and could no longer imagine eating as much as before the pilot:
I still served myself the same portions but I couldn't eat it all. Which is kind of weird for me. I stopped when I had enough. I don't know if I'm just getting used to eating a bit less or I realise that I didn't NEED to eat it all. Whereas before I would finish it because it was wasteful. But now I think, "you don't have to force yourself to eat stuff that you don't need to." And that rating of fullness at the end was quite good, because before I would have that too full, gross, feeling. But now thinking about what full feels like and overfull feels like and what not quite full feels like.
Cutting down on what I was having for breakfast did make a difference to my blood sugar before lunchtime. So just having porridge OR toast rather than porridge AND toast meant that I could have lunch at lunchtime.
Conversely, a few participants reported that their portion sizes increased, since they were hungrier than usual because they were eating less frequently:
But when I was hungry, I ate MORE. Because I was having to wait until lunchtimes until I could eat, so when I got lunch, I ate more than I normally would have. If I hadn't eaten until 1 pm, anything that wasn't tied down wasn't safe! Once I pricked my finger, I would have my meal and then the chocolate, because I better have the chocolate now else I'll have to stab my finger again. It eliminates the grazing but increased my portion sizes.
The use of Blood Glucose Monitoring. Many participants commented that their blood glucose was an unpredictable measure of their hunger:
I was having trouble with the [glucose] readings and matching it up with what I was doing, but it certainly made me think about registering whether I was hungry rather than just eating because of routine.
Super hungry didn't seem to corresponding to particularly low glucose. I did find it frustratingly inaccurate in terms of measuring my hunger, even though I was much more in touch with my hunger.
However, most participants viewed measuring their blood glucose as a useful behaviour for gaining awareness of their eating habits:
It's not just the fact that you inflict pain on yourself – it's the fact that you inflict pain and it might say "no" anyway. Really have to think, "look, am I actually feeling hungry enough?". I think it's extremely effective since it just makes you more aware. Even if I didn't hurt, it makes you aware of those wee niggle, but "I've only eating a little awhile ago". The pain element is useful and the fear of the rejection after the pain.
The psychological thing of having to prick your finger every time you want to eat is a bit of a red herring but it's quite a relevant thing. I think "hmm, I would like some afternoon tea but my fingers are a bit sore today…maybe I don't need it"
Many participants commented that the pain with finger pricking reduced after the first week:
I have the feeling that stabbing gets better. At the beginning it hurt more, but I really can't feel it anymore.
I don't find it particularly onerous. It's easy enough to fit and only a minor irritation, to prick your finger.
Source...