These are among the most common questions nutrition professionals, dietitians, personal trainers, and coaches are asked, and among the most discussed across search engines, AI assistants, podcasts, and social media. The questions are fair. The trouble is that the answers tend to arrive as universal rules, when the evidence beneath them is far more conditional.
Most popular claims begin with a real physiological observation. Somewhere between the original research and the headline, the conditions that gave the finding meaning fall away, and a strategy that suits one athlete, one session, or one goal gets repeated as advice for everyone.
This is why evidence-informed practitioners rarely stop at the first answer. Before deciding whether a strategy is appropriate, they consider the individual’s goal, the demands of the session, recovery requirements, and how it fits the wider plan. Memorising recommendations has its place, but interpreting when, why, and for whom they apply is the skill that holds up in practice.
At a glance
| Popular claim | What current evidence suggests |
|---|---|
| Training fasted burns more fat. | Fasted exercise may increase fat oxidation during a session. That is not the same as greater long-term fat loss or better performance, and it does not suit every athlete. |
| Eating every two to three hours boosts metabolism. | When total daily intake stays similar, meal frequency alone is unlikely to meaningfully change 24-hour energy expenditure. Timing still matters for appetite, recovery, and adherence. |
| Genetics determine athletic performance. | Genetics influence aspects of exercise behaviour and performance, but they are one part of a wider picture that also includes training, nutrition, recovery, environment, and consistency. |
Three Popular Sports Nutrition Claims That Deserve a Closer Look
1. Does fasted training burn more fat?
The reasoning behind fasted training is easy to follow. After an overnight fast, carbohydrate availability is lower than it would be after eating, so the body may rely more heavily on stored fat to help meet its energy demands during exercise.
From there, it is tempting to conclude that burning more fat during a workout must also result in greater fat loss over time. While the physiological mechanism is genuine, it does not answer the wider question practitioners are trying to solve.
Greater fat oxidation during exercise should not automatically be interpreted as greater long-term body fat loss.
The evidence explored in The Health Sciences Academy’s Fasting and Training resource discusses how exercising in a fasted state can alter substrate utilisation, with some studies reporting greater reliance on fat as a fuel source during moderate-intensity exercise. At the same time, the resource highlights that fuel selection during a single session represents only one aspect of a much broader performance picture.
Training intensity, glycogen availability, recovery requirements, and the objective of the session all influence whether fasted training is appropriate. A strategy that may be useful for one training adaptation may be less suitable for another, particularly when repeated high-intensity efforts or maximal power output are priorities.
Rather than asking whether fasted training is inherently beneficial, practitioners are encouraged to consider whether it aligns with the specific outcome they are trying to achieve.
Evidence-informed practitioners are less likely to ask whether fasted training “works” and more likely to ask what the session is designed to accomplish.
Questions such as the athlete’s performance goal, the intensity of the session, glycogen availability, and the demands of subsequent training sessions all contribute to the decision. Looking at these factors together allows nutrition strategies to support the wider training programme rather than focusing on one physiological response in isolation.
| Question | Evidence-informed interpretation |
|---|---|
| Does fasted training increase fat | It may increase fat oxidation during exercise under certain conditions. oxidation? |
| Does that automatically lead to greater fat loss? | Current evidence does not support making that assumption. |
| Is fasted training appropriate for everyone? | Its suitability depends on the athlete, the training session, and the desired performance outcome. |
- Fat oxidation during exercise and long-term body fat loss are not interchangeable outcomes.
- Training goals should guide nutritional strategies.
- The most appropriate approach depends on the wider performance context.
This topic is explored in greater depth inside The Health Sciences Academy’s complimentary Fasting and Training resource, part of the Evidence-to-Performance Series.
2. Does eating every two to three hours boost metabolism?
Advice to eat every two to three hours has been part of fitness culture for decades. The explanation appears logical: digesting food requires energy, so eating more frequently should keep metabolism “active” throughout the day.
Although digestion does require energy, the relationship between meal frequency and total daily energy expenditure is more complex than this explanation suggests.
The total amount of food consumed influences the energy required for digestion – not simply how often meals are eaten.
The evidence reviewed in The Health Sciences Academy’s Meal Frequency and Metabolism training distinguishes between the thermic effect of food (TEF) and total daily energy expenditure. Digesting food requires energy regardless of when meals are consumed, but distributing the same total calorie intake across more meals does not appear to meaningfully increase the total energy used for digestion over a 24-hour period.
The resource also discusses appetite regulation, an area that receives far less attention than metabolism. Some studies have found that higher meal frequencies may increase hunger and the desire to eat in certain individuals, whereas lower meal frequencies have been associated with greater feelings of satiety in some situations.
These findings suggest that meal timing should be viewed as one component of a broader nutrition strategy rather than a universal metabolic shortcut.
Rather than recommending a fixed number of meals each day, practitioners can consider whether an eating pattern supports the individual’s training schedule, recovery needs, appetite, and ability to maintain the plan over time.
The most appropriate meal pattern is not necessarily the one with the greatest number of meals. It is the one that best supports the individual’s goals while fitting realistically into their daily routine.
| Question | Evidence-informed interpretation |
|---|---|
| Does eating more frequently increase metabolism? | Meal frequency alone is unlikely to substantially increase 24-hour energy expenditure when total intake remains similar. |
| Does meal timing still matter? | Yes. It may influence appetite, recovery, training schedules, and adherence. |
| Should everyone eat every two to three hours? | No single meal pattern is appropriate for every athlete or active individual. |
- Meal frequency should not be viewed as a shortcut to a faster metabolism.
- Appetite and practical considerations differ between individuals.
- Nutrition strategies should support training, recovery, and long-term consistency.
These questions are explored in greater depth inside The Health Sciences Academy’s free Meal Frequency and Metabolism resource.
3. Can genetics determine athletic performance?
Watching elite athletes often raises the same question: are they simply born with exceptional genetics?
Genetics undoubtedly influence many aspects of human biology, including characteristics that may contribute to exercise performance. However, focusing exclusively on inherited traits can obscure the many factors that practitioners and athletes are able to influence through training and lifestyle.
Genetics influence athletic performance, but they do not determine it in isolation.
The Health Sciences Academy’s Exercise Genetics resource explores how genetics may contribute to differences in physical activity behaviour and aspects of athletic performance. It also emphasises that performance develops through the interaction of biological, behavioural, psychological, social, and environmental influences.
Training history, coaching, nutrition, recovery, sleep, motivation, and access to supportive environments all contribute to the way athletic performance develops over time. This helps explain why individuals with similar genetic characteristics may follow different performance trajectories, while others with different genetic profiles can still achieve substantial improvements through structured training and appropriate nutritional support.
Viewing genetics as one influence within a larger system provides a more balanced understanding than treating inherited characteristics as either destiny or irrelevance.
Practitioners can gain more useful insights by focusing on factors that can be modified. Understanding where nutrition, training, recovery, and behavioural strategies can support adaptation is generally more valuable than attempting to classify someone according to their genetic potential alone.
This perspective encourages conversations that identify opportunities for improvement rather than assuming that performance has already been determined.
| Question | Evidence-informed interpretation |
|---|---|
| Do genetics influence athletic performance? | Yes. They contribute to aspects of exercise behaviour and performance. |
| Do genetics determine success? | No. Performance develops through the interaction of many biological, behavioural, and environmental factors. |
| What should practitioners focus on? | Identifying modifiable factors that support long-term improvement. |
- Genetics contribute to performance but do not explain it on their own.
- Many of the factors that influence performance remain modifiable.
- Evidence-informed practice focuses on interpreting the whole picture rather than one variable in isolation.
The Health Sciences Academy’s free Exercise Genetics resource explores these interactions in greater depth, helping practitioners understand how genetics fits within the wider context of sports performance.
The Bigger Picture: Why interpretation matters
Continue exploring the evidence
The series includes four free, evidence-based trainings:
- Fasting and Training: Fasted exercise, fuel utilisation, glycogen availability, and what they mean for different goals.
- Meal Frequency and Metabolism: Meal timing, energy expenditure, appetite regulation, and the factors that influence metabolism.
- Exercise Genetics: How genetics interacts with training, recovery, behaviour, and environment.
- Training Food Pyramid™ Practitioner Tool: A practical framework for structuring nutrition before tailoring it to the individual.
Your access also reserves a place at The Health Sciences Academy’s live CPD/CEU webinar on Personalised Sports Nutrition with Alex Ruani on 17 July, where these principles are worked through in practical detail.
Quick Answers: Common Sports Nutrition Questions
Does fasted cardio burn more fat?
Should I train on an empty stomach?
Does meal frequency affect my metabolic rate?
How much does my DNA influence my fitness?
Is physical fatigue a sign of muscle failure?
Can environmental factors override "bad" exercise genes?
