Two individuals to consume Huel, a nutritionally complete powdered food as sold on Huel.com, as their sole source of nutrition for 30 days to demonstrate nutritional benefits of Huel by way of blood screening, anthropometric measurements, and feedback.
Methodology & Design
Two volunteers were selected in respect of them having no significant past medical history, an active lifestyle, professional occupations, normal BMI, no food intolerances, and normally consumed a varied omnivorous diet.
On the day they commenced the trial, the following were taken:
At the interview, the assessor provided each subject with a plan of how much Huel to consume and each was requested to keep a short diary noting how they felt and what their stools were like each day. Each subject completed a consent form and disclaimer (Appendix 1). Each subject participated in the trial in January and February 2016 for 30 days. Follow-up email correspondence occurred between the assessor and the subjects throughout the trial. On the final day of the trial, the following were taken:
Subject 1 was a 27 year old male who had not previously used Huel. He had a relatively sedentary 9-5 job and exercised three x 5km jogs per week.
After 5 days on the trial, Subject 1 was reviewed and the Huel was reduced by 2 scoops per day to a total of 380g (12 scoops) per day. He was feeling bloated on 14 scoops.
Subject 1 Feedback:
Subject 1 used vanilla Huel throughout and blended the Huel each evening for the following day. He found this easier and more pleasant. He reported following the plan to be hard to begin with but also that he ‘felt great’.
He consumed 3-4 mugs of black coffee per day during the trial. He also used sugar-free chewing gum which he found particularly pleasant to use a short while after a Huel meal.
He reported to have cravings for other foods when others around him were eating, especially at work. He particularly craved savory foods and was looking forward to consuming something savory after the trial. At the start of the trial he reported feeling full before the second Huel meal, but was craving solid food by lunchtime, but later in the day was ‘not bothered by the lack of regular food’.
Exercise, for the first few days only, was reported to be ‘hard’, but after a week, he was running 5 km in less than 28 minutes. On trial day 30, he ran 5 km in 24 mins 20 secs.
He stated that he is usually a poor sleeper but felt he slept better during the trial. It was of his opinion that this may have been due to having both a better eating and exercise routine as well as more favorable nutrition.
Subject 1 also reported that previously he suffered from frequent headaches, but during the trial had not had them and had not taken paracetamol once. He felt this may have been due to Huel or the fact that he consumed no alcohol during the trial.
His bowel movements were firm throughout, although irregular with some days not opening them, and other days opening them up to four times.
His main struggle was with the social side of Huel; he found this challenging and limiting. Not being able to consume food with friends when socializing he found very difficult, and craved what they were eating around him.
By the end of the trial, Subject 1 reported, in response to the question, "How did you feel in general?", "Really great! I feel the best I have done in a long time. My sleep patterns are regular, I don’t get headaches, and I have been satisfied and still enjoying the Huel."
He stated that he wanted to continue to use Huel after the trial, but at about 80% of his total food intake. He felt that it would have been nice to have been able to blend fruit with Huel.
Subject 2 was a 25 year old male who exercised 4-5 times per week with a mixture of weight resistance training and cardiovascular exercise, typically for over an hour per session. He had not previously used Huel. He had a relatively sedentary 9-5 job.
Subject 2 Feedback:
Subject 2 used vanilla Huel and also included the Huel Natural Flavor System flavors as he desired variety. He reported to be most fond of the strawberry and toffee flavors added to vanilla Huel.
One issue Subject 2 had was adhering to the timings as per the prescribed plan. Some days he only consumed 12 scoops of Huel. He also consumed black tea, green tea, and plenty of water. He reported Huel to satisfy his hunger, but he was ready for Huel at the meal times stipulated.
He found the main drawback with a 100% Huel diet was how it affected his socializing, especially doing things with his partner, who he reported to have ‘suffered’. For example, previously they would have have visited the cinema and had a meal out; on the Huel diet, they just visited the cinema.
Subject 2 also enjoys cooking and missed doing this on the trial.
He reported to have found sticking to a 100% Huel diet quite hard psychologically in one sense, but he did feel he felt sharper mentally, more confident, and felt his physique and muscularity had improved. When performing exercise, he felt he was stronger and more powerful. He was previously doing 3-4 pull-ups, but this increased to around 15 repetitions. He also felt his injuries were ‘better’. He reported that he felt most of the benefits to exercise performance occurred during the beginning of the trial and progress plateaued later.
He reported there to be a significant cost saving and worked out that, even if he had been purchasing the Huel, he would have saved well over £200 in a month.
He reported to have had 2-3 days where he had loose stools. He did report notable flatulence. For the last week of the trial, he had a viral infection which made him feel very rough.
Subject 2 assessed his mood throughout the trial and found it a positive experience. On days where his mood was low, it was more due to feeling tired and hungry.
He stated that he wanted to continue to use Huel after the trial, but would be re-introducing some solid food. He felt he could participate in a 3 month trial on 100% Huel, but wasn't sure if he could cope with 12 months: this was more to do with socializing and events.
|Red Blood Cells|
|Red Cell Count||x10^12/L||4.40-5.80||5.3||4.85|
|White Blood Cells|
|White Cell Count||x10^9/L||3.0-10.0||8.23||14.04*|
|Fasting Blood Glucose||mmol/L||3.5-5.8||4.5||3.9|
|Red Blood Cells|
|Red Cell Count||x10^12/L||4.40-5.80||4.54||4.6|
|White Blood Cells|
|White Cell Count||x10^9/L||3.0-10.0||5.7||5.61|
|Fasting Blood Glucose||mmol/L||3.5-5.8||4.1||4.0|
* indicates outside reference range
Discussion of Observations
Both subjects found consuming 100% Huel and no other foods with nutritional value for 30 days generally a positive experience and had no significant adverse reactions physiologically, biochemically, or psychologically.
Subject 1 had two hematological readings that were elevated prior to the trial, but improved afterwards. He did display increased neutrophils after the trial, indicating presence of an infection. His potassium level was elevated slightly but we have no pre-trial reading to compare this to; this may be due to medical issues or, more likely, is due to rupture of blood cells in the sample. His chloride level was slightly low before and after the trial. He did display slightly elevated ALT and CK liver enzyme levels after the trial; the ALT was slightly raised before the trial. These levels may have been raised in response to recent hard exercise (he reported achieving a personal best running time on the last day of the trial prior to the blood sample being taken) or possible infection.
Subject 1 displayed an improved LDL cholesterol level indicating a slight reduced risk of cardiovascular disease. His serum insulin was marginally low at the end of the trial.
Subject 1 wanted to lose some weight and body fat through the trial and achieved these goals with a 5.6 kg (12.3lb) weight loss and 2.5% drop in body fat, also improving his BMI. His WHR also improved. These benefits would be in line with reduced disease risk.
Subject 2 showed elevated liver enzymes, especially CK which was extremely raised, bilirubin, serum albumin and uric acid at the end of the trial. He reported to have had a viral infection for the final week of the trial, so it’s likely that this was the cause of these readings. His serum insulin was also very low on the final reading, which could be explained by a hypermetabolic state in the presence of infection. Other markers were in the correct, healthy ranges.
Subject 2 wanted to lose some weight and body fat through the trial and achieved these goals with a 5 kg (11lb) weight loss and 2.9% drop in body fat, also lowering his BMI. His WHR also improved. These benefits would be in line with reduced disease risk.
Both subjects found adhering to a 100% Huel nutrition diet challenging with the main limitations being the the social aspects of food. Both had normally formed stools, for the main, but did report flatulence.
Following a 100% Huel diet for 30 days with regular exercise gave no adverse blood marker reactions in either subject and any observed could be explained by the effects of exercise or infection. There were small improvements to blood lipid markers and desirable results for body weight, BMI, WHR and percentage body fat which together may indicate a slight improvement in cardiovascular and other disease risk.
Both subjects reported that they felt better on a diet where Huel provided 100% of their nutrition, although both acknowledged this may have been due to following a consistent regimen and not solely due to the nutrition provided by Huel. The main challenge reported was the limitations a 100% Huel diet puts on socializing. Both successfully adhered to their nutrition plans, but did find doing so challenging and felt that Huel being a significant part of daily nutrition, rather than 100%, would be more suited to their lifestyles. Both wish to continue using Huel on this basis.
Appendix 1 - Health Questionnaire and Disclaimer
Date of Birth:
Have you been told by a doctor that you have or have had any of the following? (please tick any that apply)
Are you currently using any medication?
If YES, please specify which and for what reasons:
Do you exclude any foods for cultural, ethnic or other personal reasons?
If yes, which foods?
Do you have any diagnosed food allergies or intolerances?
If YES please give details:
To the best of your knowledge, do you have any intolerances to the following:
Do you currently partake in any regular exercise? If so, what and how regularly?
Points to Note about the Trial
Please return this completed questionnaire to xxx. By completing this questionnaire, you agree that you’re happy to participate in the trial as outlined above.
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