Teenagers embrace ‘cut and bulk’ training as social media shapes extreme fitness habits

Teenagers are increasingly embracing the “cut and bulk” cycle and intense workout regimes promoted on social media, leading some to train most nights, count calories precisely and adopt restrictive diets, according to interviews with young gym-goers and health professionals.

Hashtags such as #shreddedphysique have been viewed billions of times on platforms like TikTok, where boys as young as 13 and 14 post videos flexing in school corridors and toilets. The cut-and-bulk approach involves a bulking phase of sustained calorie surplus to build muscle followed by a cutting phase in which calorie intake is sharply reduced to reveal more defined musculature. For a minority of teenagers this pattern becomes all-consuming, with experts warning it can affect growth, hormone health and mental wellbeing.

Fourteen-year-old George Holland began going to the gym at 11 after watching bodybuilding videos online and went on to win bronze in the under-19s category at a National Amateur Body-Builders' Association final. He said he initially trained with light weights but later moved to a gym where he could increase loads and train alongside older gym-goers. Coached by a former Mr Universe, George said he now bench-presses 140kg, squats 180kg and deadlifts 200kg. He follows a structured eating plan of six meals a day, described his current bulking intake as about 4,100 calories daily and said he will reduce to roughly 2,200 calories during a 16-week cutting phase.

Seventeen-year-old George Hazard began training at 12 with a modest home setup during lockdown. He now trains five to six nights a week and describes learning technique and programming from social media, which he says can point to primary studies if the content is credible. Hazard said gym training helped his mobility after a leg-lengthening operation and that family support has been important as he manages protein-heavy meals at home.

Eighteen-year-old Nat Walney described trying a period of "dirty bulking" in his mid-teens—consuming high amounts of ultra-processed food to grow quickly—which he said left him with persistent acne and digestive issues. Nat later adopted a raw carnivore-style diet and long fasting windows, saying he fasts for about 20 hours to improve mental clarity and uses online tools, including AI chatbots, for advice. He acknowledged some dietary approaches carry risks and said he would change course if he felt unwell.

Health professionals interviewed for this report said there is nothing inherently wrong with young people wanting to be fit, but cautioned that a focus on a single aesthetic can push teenagers toward harmful behaviours. Children's dietician Lucy Upton said the trend frequently prioritises a specific look over holistic health and that online content often mixes contextually unrelated scientific findings with personal opinion. She urged young people to scrutinise the credentials of content creators and to be wary of commercial endorsements.

Sam Grady-Graham, a GB Boxing coach, warned against restrictive eating in adolescence, noting that growth between ages 12 and 18 is rapid and requires a balanced intake from all food groups. He recommended prioritising proper movement patterns and progressive training rather than rapid escalation of load or extreme dieting.

Medical and nutrition specialists also raised concerns about potential links to disordered eating and muscle dysmorphia—the belief that one's body is insufficiently muscular despite objective size. They said prolonged calorie extremes, extended fasting and unbalanced diets can interfere with hormone production and physical development in teenagers.

Parents, coaches and clinicians interviewed suggested that young people interested in strength training should focus on age-appropriate loads, sound technique and a balanced diet tailored to growth needs rather than short-term aesthetic goals. They also recommended that adolescents and their families consult qualified health professionals before adopting restrictive diets or prolonged fasting.

The rise of early-adopting, highly visible fitness cultures underscores a broader shift in how teenagers learn about exercise and nutrition. Social media can provide access to legitimate expertise but also amplifies unvetted practices. Experts say distinguishing evidence-based guidance from anecdote or marketing is crucial as more young people engage seriously with bodybuilding and performance training.