Can Cyclists Drop Body Fat Without Being in a Calorie Deficit?

Well, wouldn’t this be the dream?

Cyclists aim to improve their power-weight ratio to make them faster, fatigue less, and more efficient. These improvements are achieved by being lighter, improving power output, or both.

It’s been well established that a calorie deficit is needed to drop body fat. Generally speaking, calorie deficits are associated with performance (and sometimes health) compromises.

As restricting calories is unfavourable for various performance markers, is there a way to drop body fat and weight by not restricting calories?

This goes against the grain and may cause you to scratch your head and question whether this is possible, but some interesting research recently published by Moro et al. (2020) suggests that you can.

Similarly to Intermittent fasting (IF), Time Restricted Eating (TRE) controls the period of the day when you are allowed to eat. Unlike many IF protocols, TRE was used as a dietary maintenance protocol for 16 elite cyclists over four weeks.

The elite-level cyclists were divided into TRE and normal eating patterns. Both groups were instructed to eat 4800 kcal daily (>700g carbs), which would theoretically not influence body weight or composition.

Each cyclist completed performance tests pre and post a typical pre-season training block (500km/week). The TRE group consumed 100% of their calories in an 8-hour eating window (10 am-6 pm), whereas the non-diet group consumed their calories between 7 am-9 pm.

Surprisingly, the TRE group dropped body weight and fat whilst preserving muscle tissue despite theoretically being at calorie maintenance, and as expected, the non-diet group maintained body composition.

The researchers also measured some blood markers – a particular hormone called adiponectin. Low levels are associated with obesity and oxidative stress, whereas high levels are associated with increased resting metabolic rate (RMR). The TRE group showed a 33% increase (vs 8% in non-diet); therefore, it was speculated that this contributed to fat loss.

However, resting metabolic rate (RMR) dropped in the TRE group and not in the non-diet group. A reduction in RMR is often seen during weight loss and calorie restriction, conflicting with the elevation in adiponectin

More interestingly, TRE peak power output increased, and by default, their Watts/kg further increased due to decreased body mass. However, VO2 max were maintained. Therefore, they significantly improved their power-weight ratio.

Lastly, the TRE group showed improvements in specific immune markers and reduced systemic inflammation and would suggest that this dieting approach could be more protective during winter.

Okay, so there are a couple of points to unpack here and, from experience working with hundreds of elite-level athletes, there’s a whopping great elephant in the room:

1) Both groups were provided with meal plans to follow. Although the reported adherence was good, I have my doubts. Under-reporting is a considerable issue with nutrition-based research and can impact the results significantly. For example, an athlete may say they’ve done or consumed XYZ, but things often get missed. Unfortunately, some athletes lie to the research team (or coach) and say they’ve implemented a strategy or habit when they haven’t.

2) Did the TRE group hit their calorie targets? Eating 700g of carbs and 4800 kcal in an 8-hour window is tough. I speculate that the cyclists could not hit their calorie targets and ended up undereating.

3) The TRE group improved specific markers of immune health, namely the ratio of neutrophils-to-lymphocytes, which correlates with C-reactive protein and increases during infection and inflammation. In other studies, when obese individuals reduce fat mass by following a moderate calorie-restricted diet without malnutrition, C-reactive protein levels and the cytokine IL-6 decrease. Therefore, is the reduction of inflammation and immune health caused by TRE or calorie restriction? Or a bit of both

Based on my interpretation of these results, the reductions in body weight, body fat, and metabolic rate result from following a calorie-restricted diet and not necessarily the specificity of eating times.

Therefore, I would make an educated guess and say that the TRE group lost weight and body fat via a calorie deficit, as the non-diet group had extra time to consume food and ate at their actual calorie maintenance.

If this were the case, TRE could be an effective strategy to drop body fat – Eating to the point of complete satiety within a confined window where you’re unable to eat anymore and still be in a calorie deficit.

I’m not going to rule out that TRE could further rationale for enhancing body composition and health, but for now, I’m not confident that this is a plausible explanation for why this happened.

Either way, regardless of the mechanism, the TRE group still got some pretty kick-ass results.

Ultimately, the headline sounds very exciting and appealing, but when you peel back the layers and see what’s really going on, there’s most likely no new surprises here. To drop body fat, you must consume fewer calories than you expend.

- Coach Chris