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OBESITY AND NUTRITION: Edited by Eric C. Westman

Brief intervention of low carbohydrate dietary advice: clinic results and a review of the literature

Oliver, David; Andrews, Kim

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Current Opinion in Endocrinology & Diabetes and Obesity: October 2021 - Volume 28 - Issue 5 - p 496-502
doi: 10.1097/MED.0000000000000665
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For a combined 32 years of being general practitioners, the authors had been giving patients weight loss advice within routine consultations according to the national health service guidelines without any noticeable success. They noted that a number of their patients were losing weight successfully using a low carb approach and decided to explore this. The aim of the clinic review was to test the effectiveness of a brief intervention of low carbohydrate dietary advice and assess the impact on weight loss in primary care patients with a raised body mass index (BMI). 

Box 1:
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This was a retrospective observational study based on data from primary care records at a single general practitioner (GP) surgery – a rural practice with 7,500 patients in Essex, UK.

Study intervention

Advice was given opportunistically to overweight (BMI > 25) patients over 16 years old with no upper age limit with the following exclusions: patients with type 1 diabetes, pregnant women, and those with a past or current history of eating disorders. Advice was given from 1st September 2018 and was coded in the patient records as 8CA4A.

Patients attended routine appointments with a GP or a practice nurse and were opportunistically given brief advice about adopting a low carbohydrate diet in order to promote weight loss. Very few patients attending were actually seeking weight loss advice as their presenting complaint.

Some of this advice was based on the successful methods used at the Norwood Surgery [1▪]. Patients’ weights were recorded opportunistically at baseline and at review appointments.

Advice was tailored to the individual patient, but typically comprised of one or a number of actions:

  • (1) Giving the patient an information leaflet that included the revised standard Norwood Surgery low carbohydrate diet sheet [1▪].
  • (2) A visual explanation of Dr Unwin's Sugar Infographics∗ [2].
  • (3) Signposting to our practice low carb website:
  • (4) Signposting to the book: ‘8 Week Blood Sugar Diet’ by Dr Michael Mosley [3].

The brief interventions were not formally timed. They were incorporated opportunistically during routine primary care 10 min appointments, without allowing extra time overall for clinics to run.

Review appointments were tailored to the patient's choice and clinical needs. Patients prescribed antihyperglycaemic and antihypertensive medications were generally offered review appointments within a few weeks to reduce any risk of side effects. De-prescribing took place when appropriate using published protocols [4].

The website was written with the specific purpose of giving patients a source of low carbohydrate material to enable them to obtain further information after the initial consultation. The aim of the website was to summarise our advice in a manner that did not overwhelm the patients and to act as a signpost to other resources for those who wanted to learn more.

We set a community weight loss target of one metric tonne (1000 kg). We tracked the progress of the total net weight loss on a ‘Weight-Loss-O-Meter’ on the notice board in our surgery waiting room.

Weight was measured using Seca weighing scales that met the expected quality standards of UK General Practice. All equipment was calibrated yearly.


As there was no control arm, the authors searched their clinical system for weight changes for each patient that occurred prior and subsequent to the low carb advice given. In this way, each patient acted as their own control to allow comparison of standard care versus the brief intervention. For each patient, changes in weight were measured for the period prior to the brief intervention (‘pre advice’) when they were receiving standard care. This was then compared to changes in weight subsequent to the brief intervention of low carbohydrate dietary advice (‘post advice’) (Fig. 1).

Study timeline. Patients had their weight measured at the time of the brief intervention and at least once in the postadvice (18 months) period. The postadvice weight loss was calculated by subtracting the most recent weight recorded from the weight recorded at the time of the brief intervention. For these patients, the clinical information system was searched for weight recordings that occurred in preadvice (one year) period. The preadvice weight loss was calculated by subtracting weight recorded at the time of the brief intervention from the earliest weight recorded in that period.

For the preadvice period

The beginning of the preadvice period was 12 months prior to the date of the brief intervention for each patient. The end of the preadvice period was the date of the brief intervention for that patient. For each patient, the authors searched the GP clinical system (SystmOne) for all recorded values of weight during this period. The pre advice weight change was calculated as the difference between the earliest and latest recorded values of weight during this period.

For the postadvice period

The study period was 18 months between 1st September 2018 and 29th February 2020. Data collection was not continued beyond this point due to the start of the COVID19 pandemic.

The weight of the patients was measured, when possible, at the time of the initial brief intervention, and measured thereafter opportunistically at subsequent visits. These values were recorded on the GP clinical system by the clinician.

The postadvice weight change was calculated as the difference between the weight measured on the date of the brief intervention and the latest weight recorded during the study period.

We used the SystmOne basic search facility to extract weight metrics into an Excel spread sheet and designed an algorithm in Visual Basic to process the data. The approach was time and resource efficient, and obviated any need to open individual patient records.

The characteristics of the weight changes were summarised using median and interquartile range. The difference in proportions of weight loss between the preadvice and postadvice was calculated using a one tailed t-test. All statistical analyses were calculated using Microsoft Excel 2010 for Windows.


In the 18 month study period, a total of 774 patients received the brief intervention of low carbohydrate dietary advice.


The patients were 332 (43%) female and 442 (57%) male. The average age was 63 years (interquartile range [IQR] 57–73 years). The patients were > 99% Caucasian.


Of the 774 patients given dietary advice, 339 of them (44%) attended for review and had their weight measured a second time. These 339 patients lost a total weight of 1,103 kg. There was a median weight loss of 2.5 kg (IQR 0.0–6.0 kg) and a mean weight loss of 3.3 kg. 107 of these 339 patients lost 5 kg or more of weight, with 29 patients losing 10 kg or more. (Fig. 3).

Pre and post dietary advice weight changes were documented in 151 patients (20%) (see Fig. 2).

Flowchart of the inclusion process. 774 patients received a brief intervention of low carbohydrate dietary advice. Out of the 774 patients, 339 returned to be re-weighed during the postadvice (18 months) study period. Of these 339 patients, 151 of them had their weight recorded in the preadvice period (12 months) preceding the intervention and were thus included.
Distribution of weight loss (kg) for patients who returned to be re-weighed (n = 339). Legend: The majority of the 339 patients lost weight. 107 of these lost 5 kg or more of weight. 29 patients lost 10 kg or more of weight.

The median weight at the beginning of the preadvice (control) period was 95.7 kg (IQR 83.1–107.5 kg). The median weight at the end of the preadvice period was 94 kg (IQR 83.8–108 kg), with a median weight loss of 0.9 kg (IQR −2 to +3 kg). The median number of days between these dates was 238 days (IQR 162–301 days) (Table 1).

Table 1 - Preadvice (control) weight changes over a period of a median of 238 days, variable for each patient (n = 151), prior to dietary advice
Start weight (kg) End weight (kg) Weight reduction for each patient (kg)
1st Quartile 83.1 83.8 −2
Median 95.7 94 0.9
3rd Quartile 107.5 108 3

The median starting weight at the time of the brief intervention was 94 kg (IQR 84–108 kg) and the median weight at the end of the study period was 93 kg (IQR 81–104.5 kg), with a median weight loss of 1.8 kg (IQR −0.5–5 kg). The median number of days between these dates was 166 days (IQR 115−235 days) (Fig. 4 and Table 2).

Distribution of weight loss (kg) for patients who returned to be re-weighed (n = 151) where preadvice weight data was available. Legend: The majority of the 151 patients lost weight. 41 of these lost 5 kg or more of weight.
Table 2 - Postadvice (intervention) weight changes over a period of a median of 166 days, variable for each patient (n = 151), after dietary advice
Start weight (kg) End weight (kg) Weight reduction for each patient (kg)
1st Quartile 83.8 81.2 −0.5
Median 94 92.9 1.8
3rd Quartile 107.5 104.5 5

The pre and postadvice difference was significant at a level of P = 0.0014.

We found that the advice was often a new concept for the patient and came as a surprise. Many patients commented that the low carbohydrate dietary advice offered something new − a new hope. Some were greatly relieved as they had spent many years attempting to lose weight without success, through various methods including commercial weight loss programmes. Our explanation of the low carbohydrate approach often appeared to serve as a sudden moment of realisation as to why previous attempts had been unsuccessful and took the onus of personal failure away.

As clinicians, we found that overcoming the sense of learned helplessness in managing chronic disease a very liberating and positive career changing experience. Whilst patients’ success in achieving lifestyle change was far from universal, our success rate in this regard was completely unprecedented in our medical careers to date.


Brief interventions regarding smoking and alcohol are established tools in UK primary care [5,6] and can be effective in helping patients with obesity lose weight [7]. This study found that a brief intervention of low carbohydrate dietary advice may be an effective tool for weight loss in patients with raised BMI, when incorporated into routine primary care, without any additional funding or time.

Recent evidence from clinical trials [8], systemic reviews and meta-analyses [9,10] support the efficacy of low carbohydrate diets for weight loss. The validity of low carbohydrate diets is now recognised by national guidelines, which endorse them as a therapeutic, nutritional approach in appropriate patients [11,12].

Raised BMI is a major risk factor for a number of chronic diseases, including type 2 diabetes [13], cardiovascular disease [13] and cancer [13]. In 2018, 63% of the population in England were estimated to have a raised BMI [14], with primary care physicians in the UK seeing the majority of these patients.

In the UK, the National Institute of Clinical Excellence and the Scottish Intercollegiate Guidelines Network (SIGN) state that healthcare practitioners working in primary care should opportunistically encourage patients to lose weight [15,16].

Analysis of almost 100,000 primary care electronic records revealed recording of weight management interventions for only 10% of patients with a raised BMI in a 17 years period from 2005 to 2012 [17]. Reasons for this are highlighted in a study exploring UK General Practitioner (GP) and practice nurse attitudes. This showed that uncertainty about obesity, concerns about alienating patients, and feelings of being unable to raise the topic within the constraints of a 10 min consultation, added to the reluctance of GPs and nurses to broach the topic of weight [18].

A UK primary care based study investigated the impact of two different 30 s brief interventions to help patients lose weight. This demonstrated that those who received active intervention including referral to a weight management group consisting of 12 1 h sessions benefited more than those who were simply advised they would benefit from weight loss. The mean weight loss of the active intervention group was 2.4 kg compared to 1.0 kg for the advice only group. Patients responded positively to this intervention [7].

A retrospective analysis of clinical data of routine work from Norwood Surgery, a similar setting in UK General Practice, measured the impact of low carbohydrate dietary advice on patients with type 2 diabetes and prediabetes. Substantial and sustained improvement in patients’ weight was demonstrated: In 128 type 2 diabetic patients consuming a low carbohydrate diet for an average of 23 months, the median weight dropped from 99.7 kg at baseline to 91.4 kg at the latest follow-up [1▪].

Our results suggest that a brief intervention of low carbohydrate dietary advice in a primary care setting resulted in significant weight loss for patients with a raised BMI. Our patients surpassed the 1000 kg community weight loss target and the level of interest and engagement the ‘Weight-Loss-O-Meter’ engendered in our patients was an unexpected delight for us as busy clinicians.

Primary care represents an important setting in which patients with a raised BMI may access weight loss interventions. Access to appropriate weight management interventions for patients in primary care is of increasing importance in the context of a national objective to establish a downward trend in obesity among UK adults [19]. Given that most patients consult their primary care clinician at least once a year, and many, several times a year – this brief intervention is highly practical.

Although the use of low carbohydrate diets is in line with BDA and SIGN guidelines for type 2 diabetes [11,12], this type of dietary advice still remains controversial within the medical community [20].

A medication review appointment proved to be a useful opportunity to provide this dietary advice. Many patients found the possibility of reducing their medication a significant incentive to engage with our advice. In a number of cases when appropriate, we gave patients the choice of engaging with this advice or starting new medication, which some patients responded positively to.

Maintaining a register of all adults with obesity in general practice is a clinical management area of the Quality Outcomes Framework and indicators related to consequent interventions are being introduced for the first time in 2021. Prior to 2021, unlike for smoking, GPs had not been specifically encouraged to record whether or not weight management is discussed and there was no national surveillance system for recording weight loss interventions.

Healthcare Practitioners working in primary care settings have the important responsibility of overseeing their patients’ general health and welfare. Primary care patients are asked about diet in health checks and chronic disease management thus providing ample opportunity for discussion. This study shows that brief intervention in the form of structured dietary advice, signposting and behaviour change counselling, can fit within routine appointment times and be delivered by primary care clinicians with successful outcomes.

Strengths and limitations

This was a retrospective observational study and therefore does not represent the highest grade of evidence. The strength of this study is the ‘real world’ brief intervention nature but the main limitation is the high loss to follow up.

Follow up arrangements were based on clinical need, rather than a study protocol. Only 44% of patients given dietary advice returned to be reweighed before the end of the study period, which was curtailed by the onset of the COVID19 pandemic. Preadvice and postadvice data were only available for 20% of the study population.

Measuring weight opportunistically at follow-up appointments may have theoretically introduced a selection bias; (1) from the patient deciding whether to make a follow-up appointment or not, and (2) from the clinician potentially selectively recording weight measurements both at the initial and review appointments. We only included patients for whom we had recorded weight measurements in the year prior to the intervention, which may potentially have introduced a selection bias.

The weight changes were seen over a short time period (median 166 days) and therefore do not provide information regarding the long term effectiveness of the intervention.

Comparison with existing literature

Prior studies have shown that brief interventions for obesity can be effective within a primary care setting [7]. The use of low carbohydrate dietary advice as a brief intervention for raised BMI has not previously been assessed – it is therefore not possible to compare these findings with existing literature.


There is no published literature available assessing the efficacy of brief low carbohydrate dietary advice. Low carbohydrate dietary advice may be a promising effective brief intervention for raised BMI within a UK primary care setting. There is potential for any clinician to adopt these methods. A larger scale, longer term, prospective trial may deliver a higher grade of evidence than the evidence presented in this study.


Thanks to Tara Kelly and Christine Delon for their input.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


Papers of particular interest, published within the annual period of review, have been highlighted as:

▪ of special interest

▪▪ of outstanding interest


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2. Unwin D, Haslam D, Livesey G. It is the glycaemic response to, not the carbohydrate content of food that matters in diabetes and obesity: The glycaemic index revisited,. J Insulin Resis 2016; 1:a8.
3. Mosley M. The 8-Week Blood Sugar Diet: Lose weight fast and reprogramme your body, Reprint Edition. London: Short Books; 2015.
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brief intervention; low carbohydrate diet; raised BMI

Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.