In your health club there will be cardiovascular equipment which features training zones relating to your level of effort. Common descriptions include ‘fitness’ (high intensity), ‘aerobic’ (medium intensity) and ‘fat burning’ (low intensity). The theory is that at low intensity the body burns fat and as intensity increases less fat is metabolised as the body burns more carbohydrate. Consequently anyone wanting to burn fat is drawn towards low intensity exercise to achieve their goal.

The problem with these zones is that – although sound in principle – training in the fat burning zone it isn’t the most effective way to raise metabolic rate and burn more fat. The reasons for this are simple:

When training at low intensity the body is able to access the majority of the required energy from fat stores. As intensity increases the body requires more energy so begins to access stored carbohydrate as it provides a quicker source of energy. The percentage of fat consumed therefore drops and the percentage of carbohydrate consumption increases as the effort becomes harder.

For an endurance athlete it’s essential to train the body to use fat as the primary fuel source. This is primarily because carbohydrate stores are limited and can’t generally be ingested fast enough to prevent fatigue. Therefore the more efficient endurance athletes are at fat burning the longer they’ll be able to maintain their pace without depending on carbohydrate. An efficient fat burning endurance athlete is consequently toned and lean with a low body fat percentage.

For people following this principle to lose weight the following points must be considered:

  • Unless you’re training 1-2 times every day you simply won’t be burning enough calories in the ‘fat burning’ zone to achieve the desired fat loss
  • The more fatigued a muscle is the more calories it will burn – therefore the harder you work the more calories you will burn
  • Muscle tissue is metabolically very active so training should include work which stimulates muscle development – low intensity training does not achieve this


Training in the ‘fat burning’ zone is essential for endurance athletes so they’re able to race faster and longer, but this requires many hours of low intensity training every week. For someone who specifically wants to reduce body fat a combination of cardiovascular training, high intensity interval work and resistance training is required.