Eating Habits and Weight Loss – Dispelling Some Myths

Dean Zweck | 03 Jan 2018

There are many words that can cause an argument on social media, and nutrition is certainly one of them. It’s great to see so many people passionate about what we put in our bodies, but time and time again, I see PTs basing their opinions on their own dogma, based on “well I did it and it worked for me” or “my clients do it all the time and they get great results, so it must be true”. I was definitely in that camp until I invested in my own education with Precision Nutrition and soon to graduate from Mac-Nutrition Uni. I want to shed some light on some of the common current nutrition beliefs.

Fasted Cardio Burns More Fat

A traditional body building tactic now gaining more and more media attention, the myth is that doing cardio first thing in the morning burns more fat. It does! But this doesn’t mean that you end up losing more body fat! Let me explain...

While fasted cardio does burn more fat during the exercise itself, you burn LESS fat over the rest of the day to compensate (Schoenfeld et al., 2014). Using fat or carbohydrate as the predominant fuel in exercise is measured by your respiratory exchange ratio (RER), which is the ratio between the amount of carbon dioxide (CO2) produced in metabolism and oxygen (O2) used.

Also, fasted cardio uses intramuscular triglycerides as the main source of fat during the exercise, NOT subcutaneous or visceral body fat (De Brock et al., 2008).

Fasted cardio has its place. If it’s the only time you can do your cardio and you prefer to do that fasted, go ahead. There is nothing wrong with it, just there is no advantage to it. Schoenfeld (2014) did a great RCT on this which you can read here.

Never Skip Breakfast If You Want to Lose Weight

So fasted cardio brings us nicely on to the topic of breakfast. “You must eat first thing in the morning to kickstart your metabolism” or “If you want to function you need fuel to do so”. I have 100% said this in the past. I’ve even heard trainers say it’s more important to eat food off their lap in the car when driving than to skip breakfast! Crazy! But is there any truth in skipping breakfast being any better for losing weight?

People who skip breakfast tend to be less health seeking. They have a tendency to not sleep well, are too busy for breakfast, may only have a coffee all morning so by the time lunch comes, they are extremely hungry. They have no food prepped and reach for the nearest highly caloric convenience food they can grab. They then come home to takeaways, or have a lot of meals out, consume too much alcohol and the list goes on!

Sound familiar? Like many of my clients! However, it isn’t skipping breakfast that is the problem. It is the anti-health behaviors that follow that cause weight gain and illness. Shlundt et al. (1992) stratified two groups based on baseline breakfast eating habits: those that ate breakfast and those that didn’t. Both groups were then randomly assigned a 2x vs 3x meal/day eating plan. (no breakfast vs breakfast)

The results were extremely interesting.

Baseline breakfast eaters:

  • Lost 8.9kg in the no-breakfast treatment
  • Lost 6.2kg in the breakfast treatment

Baseline breakfast skippers:

  • Lost 7.7kg in the breakfast treatment
  • Lost 6.0kg in the no-breakfast treatment

What can we tell from this. Well firstly, you will still lose weight whether you eat breakfast or not. Calories in vs calories out is still king. Secondly, the group that had to disrupt their eating habits the most to comply with their treatment had the best results.

Removing breakfast from someone who is used to eating it will lose weight, you have just removed a meal from their day so it makes sense. Someone who usually skips breakfast, who now potentially has to wake up earlier to comply, may just make BETTER choices over the rest of the day.

Eating breakfast is down to preference again. And if you can help your clients make good choices over the whole day, eating breakfast or not has little significance on the results you will get.

Eat Little and Often to Boost Your Metabolism

Finally, eating little and often! So, if training fasted doesn’t work, and eating breakfast has little effect, what about meal frequency?

Again, I’ll hold my hands up and say I’ve definitely been guilty of this. The research doesn’t back up this view. As we eat, there is a small increase in metabolism, so we can be forgiven for thinking that the more we eat the more our metabolism boosts. Unfortunately, this is not entirely the case.

Tai et al. (1991) looked at the thermic effect of meal sizes, 1x 750kcal meal vs 6x 125kcal meals over 3 hours. The larger meal boosted metabolism more than the smaller more frequent meals. This was still only 16 kcals over 5 hours. For more information click here.

Cameron et al. (2010) found no difference in weight loss for 6 meals/day vs 3 meals/day and Bellisle et al. (1997) found no increase in metabolism between nibbling and gorging!

Meal frequency does matter more if your goal is muscle gain. However, for fat loss it again comes down to personal preference. Think about it from a client’s point of view, Mom of three kids whose day revolves around dropping kids off at school and various activities in the evenings, house work, shopping, cooking, paying the bills, maybe a bit of work too. Tell her she needs to eat every 2-3 hours and you are setting both her and you up for FAILURE.

Find a frequency that works for your client that gives them the correct calories for their goal and you may be on to a winner!


Sadly, we as trainers are always looking for short cuts to success with our clients, a magic strategy that yields amazing results. But, these approaches don’t hold up to scrutiny when we look at the science and studies.

As boring as it sounds, it tends to come back to calorie balance and client preference/adherence!

The world of nutrition is confusing, and I wholeheartedly believe that every trainer who is interested in this field undertake some continued professional development. My personal recommendation is the 12-month course, which has been transformation for me in terms of my knowledge, belief and application.


Schoenfeld, B., Aragon, A.A., Wilborn, C.D., Krieger, J.W., & Sonmez, G.T. (2014). Body composition changes associated with fasted versus non-fasted aerobic exercise. Journal of the International Society of Sports Nutrition,11,54.

De Bock, K., Derave, W., Eijnde, B.O., Hesselink, M.K., Koninckx, E., Rose, A.J., Schrauwen, P., Bonen, A., Richter, E.A., & Hespel, P. (2008). Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake. Journal of Applied Physiology, 104 (4), 1045-1055. 10.1152/japplphysiol.01195.2007.

Schlundt, D.G., Hill, J.O., Sbrocco, T., & Pope-Cordle, J. (1992). The role of breakfast in the treatment of obesity: A randomized clinical trial. The American Journal of Clinical Nutrition, 55(3), 645-651.

Tai, M.M., Castillo, P., & Pi-Sunyer, F.X. (1991). Meal size and frequency: effect on the thermic effect of food. The American Journal of Clinical Nutrition, 54(5), 783-787.

Cameron, J.D., Cyr, M.J., & Doucet, E. (2010). Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet. British Journal of Nutrition, 103(8), 1098-1101. doi: 10.1017/S0007114509992984.

Bellisle, F., McDevitt, R., & Prentice, A.M. (1997). Meal frequency and energy balance. British Journal of Nutrition, 77, Suppl 1, S57-70.

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Dean Zweck

About the author: Dean Zweck

Dean Zweck, BSc, CPT, has been in the industry for 17 years with 13 as a personal trainer. For the last 7 years, he has been the lead educator for PTs in the UKs largest commercial gym chain, as well as successfully owning his own PT business. Dean's passion is helping trainers acquire all the tools so they can get clients, train clients and keep clients. The three core skills all successful PTs need to have.

In his spare time, Dean is a bit of an adrenaline junkie competing in OCRs with Europe's Toughest Mudder on the agenda for this year, plus engaging in mountain biking and rock climbing.

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