In the diet world, it can be difficult to sort the facts from the myths and while the idea behind negative calorie foods is based on a scientific theory; it has not been proven by research. It is true that the thermic effect occurring in reaction to the food you have just ingested can expend some of the calories you consume, but there is no evidence to state this can outweigh the calories consumed and create a calorie deficit.
With that being said food which has been labelled as negative calorie does help aid weight loss due to the fact that it is nutrient-rich and low calorie. The majority of fruits and vegetables on the list have high water contents and provide us with a good amount of dietary fibre to aid nutrient absorption and digestion.
Celery is the most talked about of all the ‘negative calorie’ foods which seemed to kick start this diet craze. The reasons behind celery being hailed as negative calorie are partially due to its high water and very low calorie content. It is also due to the way in which the nutrients of celery are ‘sealed’ within its complex structure making our digestive systems work much harder in order to retrieve the energy from this food. In this respect, around 30-40% of the calories consumed from celery can be burned off during digestion.
Celery is also a great source of calcium which helps to enhance the endocrine system causing hormone alterations which aid fat release and breakdown. The texture of celery can also help to satiate hunger with minimal calories due to the increase in length of time we spend eating it as well as digesting it.
Lettuce only provides ~15kcal per 100g which is why it is such a great addition to salads. It is also a store house of phytonutrients which promote health and help to protect against chronic diseases. Lettuce is abundant with vitamin A and beta-carotenes which are essential for vision and healthy skin as well as mucus membranes within the body. The vitamin K in lettuce is fundamental to bone health while the array of minerals present (iron, calcium, potassium and magnesium) are essential to cardiovascular health and skeletal muscle development and repair.
Lettuce may not provide you with fewer calories than you need for digestion, but it does provide you with an excellent line up of micronutrients with minimal calories.
The average sized orange provides only 85kcal of energy and is a great snack choice. Not only this, but it quenches thirst and is a far better alternative to drinking a large glass of orange juice which is likely to be packed with excess sugar and preservatives. Oranges are an excellent source of folate which is essential to DNA synthesis. They are also a good source of potassium, fibre and of course vitamin C! Vitamin C is known for its anti-inflammatory and anti-oxidant powers essential to immune health.
There are roughly 18 calories in an average chili pepper. Spicy food has recently come to the forefront in the diet world as an effective aid to weight loss and rightly so. The thermic effect caused by ingesting ‘hot’ foods gives metabolism a boost, but that is not the only reason for eating chili peppers. They help to protect the stomach lining and prevent gastric damage in small quantities, they have anti-inflammatory properties and research has shown that the capsaicin found in these peppers is able to kill pancreatic and lung cancer cells without damaging the surrounding healthy cells. If this still isn’t enough to tempt you into eating a spicy pepper, they can reduce cholesterol and are a good source of vitamin C too.
Strawberries are another popular fruit on the negative calorie list. At only 32kcal per 100g it is easy to see why these berries have been associated with this theory. As well as being a delicious and filling snack, strawberries contain high levels of anthocyanins, ellagic acid, vitamin C and vitamin B complex. Add to this the fact that strawberries are mineral dense and you have yourself a nutrient power house berry! Associated with having anti-cancer, anti-inflammatory and anti-aging properties, strawberries also help protect the nervous system, particularly the brain.
Eating a whole carrot is a brilliant snack. Yes, people might think you are impersonating a rabbit but who cares when it is so good for you! The reason I suggest you eat it in this way (as opposed to cutting it into batons) is that it takes longer to eat a whole carrot and this helps you to feel full quicker. It also seems like a much bigger snack than a few slices of carrot even when it is the exact same quantity. The structure of carrot makes it relatively difficult to digest which increases the energy required to extract the nutrients. Carrots are a particularly good source of fibre and an array of vitamins including vitamin C and A. Vitamin A is necessary for good vision which is where the phrase ‘carrots can help you see in the dark’ comes from.
Tomatoes are a juicy and delicious fruit providing only ~18 calories per 100g and they are so easy to implement in a healthy eating plan. Not only can you use them in salad, there are great to create your own healthy sauce to help liven up meals which are dry and less enticing than they ought to be. Tomatoes contain lycopene which is an anti-oxidant with anti-cancer properties. Like other foods on this list, tomatoes are vitamin and mineral dense with minimal calories.
Cucumbers are a brilliant low calorie (only 15kcal per 100g) addition to a healthy diet because they are predominantly made up of water. Cucumbers are known for having a mild diuretic effect, stimulating the kidneys and aiding detoxification which is why they are associated so closely with weight loss and ‘negative’ calories. Cucumbers contain ~147mg potassium per 100g and the skin provides a good source of fibre.
While the nutrition on the negative calorie food list is yet to be proven to provide fewer calories than the energy used in digestion, they are proven to help aid weight loss when eaten as part of a healthy diet.