Sugar diet: Why are some athletes eating sweets to lose fat?

"I had Sour Patch Kids, Starburst, gummy bears, and apple juice for breakfast." No, this isn't a child's confession after raiding the pantry, but a statement from Mark Bell, a renowned strength athlete who has bewildered his followers by radically changing his nutritional approach. What's happening when these advocates of low-carb nutrition suddenly start consuming enormous amounts of pure sugar and, surprisingly, achieve impressive fat loss results?

The "sugar fasting" controversy

The idea seems counterproductive to the point of being absurd: consuming primarily refined sugar while seeking to lose body fat. Mark Bell and others like Cole Robinson (creator of the "Snake Diet") have generated considerable controversy with this extreme approach, provoking reactions ranging from scientific curiosity to genuine concern.

However, before dismissing this strategy as another passing fad or, worse yet, adopting it without understanding its foundations, it's essential to understand the science behind it and recognize:

It's not suitable for most people
It requires very specific conditions to work
It carries considerable long-term risks

The key molecule: FGF-21 and its metabolic role

Behind this controversial approach lies a biochemical foundation: a messenger molecule called FGF-21 (Fibroblast Growth Factor 21). This protein acts as a powerful metabolic regulator with notable effects:

Increases energy expenditure: Significantly increases metabolic rate
Promotes "uncoupling": Allows energy to dissipate as heat from mitochondria
Favors fat utilization: When activated under the right conditions

What activates FGF-21? Consuming pure sucrose (table sugar) —not starches or other complex carbohydrates— can trigger the production of this molecule, especially when other specific metabolic conditions are met.

The necessary conditions for it to work (if it works)

It's not enough to simply add sugar to your diet. For this strategy to have any chance of success, it requires:

Significant caloric deficit: Despite high sugar consumption, total caloric intake must remain below expenditure
Extremely low dietary fat: Practically zero fats in the diet
History of low-carb diet: Works better in people who have previously followed ketogenic or low-carb diets
Moderate to low protein: Contrary to many fat loss approaches, protein is deliberately kept low
Intense training: Combination of weightlifting and high-intensity sprints

Most importantly, understand that this is NOT simply "eating sugar to lose weight," but an extremely specific protocol with precise metabolic requirements.

Who might benefit? (and who definitely shouldn't try it)

Potential candidates:

Already lean athletes: People with low body fat percentage and metabolically healthy
Individuals with previous ketosis experience: Those who have "trained" their cellular machinery to efficiently use fat
People with time to train intensely: The protocol requires significant physical activity

Who should NOT consider this approach:

People with overweight or obesity: Research shows that in these cases, FGF-21 is already elevated but there's "resistance" to its effects
Diabetics or prediabetics: Can worsen insulin resistance
People with sedentary work schedules: Without adequate physical activity, it's probably counterproductive
Older individuals: FGF-21 sensitivity decreases with age

The science behind why it might work for some

A study published in the Journal of Obesity and Diabetes Metabolism found that overweight or obese people already have elevated FGF-21 levels, but their tissues don't respond correctly to this signal —similar to what happens with insulin in type 2 diabetes.

For lean athletes like Mark Bell, the proposed mechanisms include:

Adapted cellular machinery: Years of low-carb diet have "trained" their cells to seek and use fat
Dietary fat deficit: By almost completely eliminating dietary fat while their cells are programmed to use it, their body aggressively turns to body fat stores
Functional FGF-21 increase: Unlike people with obesity, their tissues respond effectively to this metabolic signal
Anticatabolic effect of carbohydrates: High carbohydrate consumption helps preserve muscle mass during deficit

Potential risks and considerations

Even for the few people who might benefit from this approach, there are important concerns:

Sustainability: Hardly maintainable long-term
Inflammatory response: High sugar consumption can increase inflammatory markers
Dental health: Obvious risk to teeth
Hormonal dysregulation: Possible effects on long-term insulin sensitivity
Psychological relationship with food: Can promote disordered eating patterns

Safer alternatives that leverage similar mechanisms

If you're intrigued by this approach but (sensibly) don't want to venture into the extreme of the sugar diet, consider these alternatives:

Intermittent fasting: Can naturally increase FGF-21 without the risks of high sugar consumption
Moderate caloric deficit with low fat: A more balanced approach that can achieve similar results
High-intensity interval training: Stimulates many of the same metabolic pathways
Carbohydrate cycling: Alternating high and low consumption days to obtain metabolic benefits without the extremes

Conclusion: Scientific perspective on an extreme approach

The sugar diet represents a fascinating case where understanding specific metabolic pathways has led to an extreme protocol with surprising results for a very specific subset of people.

For most, however, this approach is inadequate and potentially harmful. The science behind FGF-21 is legitimate, but its application through massive sugar consumption remains in experimental territory.

As with any extreme nutritional approach, moderation, common sense, and individualization remain the most solid principles for most people seeking to improve their body composition long-term.