Food Energy

Key points

• Food energy is expressed in calories (kcal). Per unit weight, fat contains roughly twice the energy of protein or carbohydrate.
• Approximate values: fat 9 kcal/g · carbohydrate 4 kcal/g · protein 4 kcal/g · alcohol 7 kcal/g.
• NICE bariatric surgery referral thresholds: BMI 40 kg/m² or more · or BMI 35-40 kg/m² with a significant comorbidity that could improve with weight loss (such as type 2 diabetes or hypertension) · consider earlier assessment in people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family origin, using lower thresholds.
• Orlistat is the licensed oral pharmacological option alongside lifestyle measures · GLP-1 receptor agonists (liraglutide, semaglutide) and tirzepatide are now NICE-approved options within specialist weight-management services.
• Sibutramine and rimonabant were withdrawn worldwide (2010 and 2008) for cardiovascular and psychiatric safety respectively, and are no longer treatment options.

Decision points in this pathway

• BMI 40 kg/m² or more, OR 35-40 kg/m² with a significant comorbidity that could improve with weight loss?

The full step-by-step algorithm, including what to do at each branch, opens in the app for approved members.