Psychology of carb colours

We recently updated our athletes on a change to the carb colour coding. Athletes noticed a little more GREEN and YELLOW appearing on their weekly plan view. Rest assured, we were not suddenly stuffing our athletes full of carbs. We reviewed the thresholds for what we considered a lower day, a moderate day and a higher day. As such, we reduced the threshold for what constitutes these colours. Thus a lower amount of carbs per kilogram now dictated the day's colour. To illustrate this, we have provided the old and the new coding for a day’s overview.  If you are familiar with the updates, scroll to the bottom to see the survey results.


We offered a 30 minute consultation (worth $250USD) to everyone who submitted their responses. The athlete who has won this competition is...

Rachel Brown. Congratulations Rachel - you can book your appointment with Scott at anytime that suits you.



This is what we originally used to help calculate the overall day’s colour in Fuelin. 

Red Day = </= 3.2g/kg/bodyweight.
Yellow Day = 3.2-5.2g/kg/bodyweight
Green Day = >5.2g/kg/bodyweight


This is what we have updated the calculations to determine the overall day’s colour in Fuelin. As you can see, we have significantly reduced the threshold for a yellow day. 

Red Day = </= 1.8g/kg/bodyweight.
Yellow Day = 1.8-4.0g/kg/bodyweight
Green Day = >4g/kg/bodyweight

The reason we have updated this is that we felt the threshold was too high for what constituted a lower, moderate and higher day. This was potentially negatively impacting some athletes psychologically. This was due to some feedback about being under the impression that they were always on low-carb plans. This was not the case, as illustrated by the examples below. A lower-carb day would, by definition, be ~50g/day carbohydrates, and potentially even under 100g/day could constitute a lower-carb day. Athletes on Fuelin will never have a carb amount set as low as that unless there is a specific individual case that warrants it.


It is important to recognize that the amount of carbs per meal stays the same.  This is where some athletes may get confused with how a day’s colour can be yellow, yet all their meals are red. It is the cumulative amount of carbs relative to the athlete’s body weight that will decide the day’s colour. If the total amount of carbs made up by all the meals in the day adds up to a total value of >1.8g/kg/bodyweight, then the day’s colour will be either yellow or green. 

Red Meal ~ 30g
Yellow Meal ~ 50g
Green Meal ~ 100g

Examples of how new thresholds have impacted the day's colour.

E.g.1. 60kg/132lb female athlete

150g carbs per day provided This equates to 2.5g/kg/bodyweight and therefore is now a yellow day. Previously, this would have been a RED day as it is <3.2g/kg/BW. Eating 150g of carbs is certainly not low carb and, based on the athlete size, not lower carb either. The actual day view could have 5 RED meals to make up 150g. Thus, you can see all RED meals in a day, yet the day's colour could still be YELLOW.

E.g.2. 85kg/187lb male athlete

200g carbs per day provided. This equates to 2.29g/kg/bodyweight and therefore is now a YELLOW day. Previously, this would have been a RED day as it is <3.2g/kg/BW. Eating 200g of carbs is certainly not low carb and, based on the athlete's size, not lower carb either. The actual day view could have 3 RED and 2 YELLOW meals to make up 200g. Thus, you can see a lot of RED meals in a day, yet the day's colour could be YELLOW.


We appreciate that this update could have also worked in reverse. Some athletes might have been a little distressed by seeing GREEN and YELLOW days more frequently. The psychology of the power of the colours is not lost on us. We wanted to know what the Fuelin athletes thought of the change. We had a 30% response rate to the questionnaire at the time of writing this article and will update the data as more responses are submitted online.


It was important to get a clear picture from all our athlete's genders to ensure the impact was not biased. A very even split was achieved. We can therefore be confident that the other questions are a fair representation of the Fuelin communities' attitude to carb colours and what they mean to each gender.                                                                                                                                   


This was really pleasing to see. The comments that were provided by athletes were really, really inspiring to us. It confirms we are doing a great job in educating athletes on the importance of carbohydrates, total energy intake and the effect that this has on health & performance. 

Examples of comments left in the survey include:

“I am trying to fix myself..... fatigue, dizziness, training. and get back on track after three years of slowly possibly going into Red-s and ... nearly getting divorced. I am/ was, in and out of being just a shell of a person, there physically, yet never mentally and unable to think or feel. I am now trying to fix my life with Fuelin's help.”

“Because the carbs are healthy, nutritious carbs, not processed junk. :)

“The new thresholds are more realistic, and the colour coding is helpful. However, it’s more important to read the colour coding in conjunction with the daily specified macros.”

“I trust the Fuelin app to decide the correct amount of carbs per my training schedule.”

“I've been with FuelIn for ~6+ months and I just trust the process.”

“It means I feel I’m fuelling my upcoming sessions and day appropriately.”

“I actually worried more about my performance on workouts when I saw so many red days initially.”

“I love carbs!”

“I trust the program.”

SEE NO EVIL?                                                                                                                                                        

Again, this was refreshing to see & read. The old way of thinking for athletes requiring low-carb fueling to hit goals is slowly shifting. For nearly 90% of our athletes, we are seeing a “no fear of carbs” mentality.  The reassuring point made by so many athletes in their comments was related to fueling for the work being completed and an understanding of increasing amounts of carbs when the training called for it. The educational upskilling aspect of Fuelin is super important to us. Athletes are becoming better informed on the need for carbohydrates specific to their workouts. It is not a blanket; you need heaps of carbs; it is more the notion of using specific types of carbs and specific amounts when required. The negative implications for “red” meals were also highlighted, which shows that further work is required to educate athletes not to equate red with “good v bad.” It is more about “low v high.”

“Again, I would just follow the carb goals per meal and per day. I find the colours per meal are really helpful. But for the overall day colour, I look at the specific goals.”

“I find red associated with negative connotations. I love carbs.”

“It's hard to get excited about red; it makes me feel like I'm doing something wrong or am being punished.”

“I don’t mind seeing red if it means I need to reduce- I like seeing them at the time I should have less carb; I try and see the colours as the type of carb I’m having.”

“I prefer to see yellow or green since it makes me feel like I will perform better in each session.”

“I’ve been an endurance athlete for about ten years and tried to stick to a low-carb diet for most of that time - I think this fueled a poor relationship with food and disordered eating and hurt my performance. I’m done with the low-carb mentality - it may work for non-athletes, but not for someone who pushes their body day in and day out. The message out there has to change - carbs are not bad, especially for athletes.”

“I'm not bothered by the colour. At first glance, I know immediately if it will be low, moderate or high, and then figure out what the number and type of carbs should be like for that meal.”

“It’s the meal breakdowns that drive what I eat, so based on the new explanation, when I see the yellow and green for the days, I’ll know it’s a higher calorie day, but I still need to see the day-to-know what to plan for at meals.”

“I would be worried about being under-fuelled, seeing a lot of red carb days.” 


This question was aimed at understanding if the colour of the day impacted the athlete's psychology depending on the athlete’s purpose, i.e. performance goals or improving body composition goals. It was a fairly even split between yes and no with this one. Diving into the responses, it became clear that if an athlete was in a performance-driven phase, the colour yellow or green had a positive impact on the athlete, whereas if red was seen, this was often viewed with trepidation and feelings of lower energy.  The reverse was seen when athletes were in body composition focus and often associated red with lower carbs and ultimately lower calorie intake to support their intended goal.  The carb colour was also seen as a reminder about the specificity of carb type in relation to the intensity of the training being completed. This was a good learning and reinforces the notion that athletes are learning the specific types of fuel to use in relation to the intensity of the sessions. 

“If I am doing z1 workouts, FUELIN helps remind me that I don't need as many carbs, whereas I need more carbs for z4+ work.”

“I want to make sure I’m performing/recovering at my best. If I wasn’t training, I prefer to eat less carb.”

“I see food very much as fuel; I'm not a "foodie" at all. So eating to improve my training is something that means a lot to me.”

“I think that I trust the program enough to try and follow it regardless of my goals. That said, if I'm trying to lose weight, I may wonder about a lack of red.”

“I just want to be fueled properly for my training prescribed in my plan.”

“When I am training hard in a week, I want to see green. When low training weeks seeing red keeps me accountable, from overeating.”

“When I'm more focused on training, and training more, I expect to see more yellow and green days.”

“I said yes, but really it depends. If I have a high-intensity session and my day is red, I'll look at my meals to understand why.”

“Other body composition goals are important to me; it’s mostly about performance. I don’t want to see a red day when I have a hard workout planned.”

“I'm very plan and detail-oriented, so for me, it really is more about knowing the types of carbs and the number for the day and individual meals. The color influences that thinking but does not impact my mindset.”

“I try to be more purposeful when I eat for training. I am not perfect at all, but as an older post-menopausal athlete, everything is HARDER. Since I have been fueling better, the results have been better. And I LIKE that a LOT!”

“I’m not afraid of carbs, so I eat as many as possible!”

Thank you for reading and thank you for helping us; help you.

Fueling you,


Scott Tindal
May 6, 2024
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