What Are Negative Calorie Foods
Have you heard of 'negative calorie foods'? These are foods supposedly so low in calories that your body burns more energy digesting them than they actually contain. Sounds too good to be true, right? Well, it may be. The concept of negative calorie foods has gained significant popularity in weight loss circles, particularly among women seeking effective ways to manage their weight. However, it's crucial to separate fact from fiction and understand the scientific reality behind this appealing but misleading concept.
Women's Health and Weight Loss
Weight management often presents unique challenges for women. Hormonal fluctuations throughout the menstrual cycle, pregnancy, and menopause can significantly impact metabolism and food cravings. Additionally, societal pressures and unrealistic beauty standards can lead to unhealthy relationships with food and body image. According to the NHS, nearly 60% of women in England are classified as overweight or obese
This statistic underscores the importance of promoting evidence-based, sustainable approaches to weight management rather than quick fixes or fad diets.
Understanding Calorie Burning and Digestion
The Thermic Effect of Food (TEF) Explained
The thermic effect of food (TEF), also known as diet-induced thermogenesis, refers to the energy expended by our bodies in the process of digesting, absorbing, and metabolising the food we consume. This concept is fundamental to understanding why the idea of "negative calorie foods" is more myth than reality. According to University of Sydney: "The thermic effect of food is real, but its impact on overall calorie expenditure is often overestimated. While some foods do require more energy to digest than others, no food has a negative calorie impact
Different macronutrients have varying thermic effects
- Protein: 20-30% of its energy content used for digestion
- Carbohydrates: 5-10% of its energy content used for digestion
- Fats: 0-3% of its energy content used for digestion
TEF and "Negative Calorie Foods"
The thermic effect of food typically accounts for about 10% of our total daily energy expenditure. This means that if you consume 2,000 calories per day, approximately 200 calories are burned through the process of digestion and metabolism. However, even foods that are very low in calories, such as celery or cucumber, still provide more energy than is expended in their digestion. For example, a 50-calorie serving of celery might require about 5 calories to digest, leaving a net gain of 45 calories.
The Myth of Negative Calorie Foods Debunked
Scientific Evidence
Despite the popularity of the concept, there is no scientific evidence supporting the existence of negative calorie foods. A study published on bioRxiv examined the validity of negative calorie foods using bearded dragons and celery. This empirical study found that the lizards gained a net 24% of the celery meal's energy, refuting the existence of negative calorie foods.
From an evolutionary perspective, it wouldn't make sense for our bodies to expend more energy digesting food than we gain from it. Our bodies are designed to efficiently extract and utilise energy from the foods we consume to support vital functions and survival.
Focus on Healthy Eating Habits
Rather than pursuing the myth of negative calorie foods, we would be better served by focusing on building sustainable and balanced eating habits. The NHS Eatwell Guide provides an excellent framework for creating a nutritious diet that supports overall health and weight management
Some examples of healthy, low-calorie foods that can be beneficial for women include
- Leafy greens (spinach, kale, rocket)
- Cruciferous vegetables (broccoli, cauliflower, Brussels sprouts)
- Berries (strawberries, blueberries, raspberries)
- Lean proteins (chicken breast, fish, tofu)
- Whole grains (quinoa, brown rice, oats)
These foods are not only low in calories but also rich in essential nutrients, fibre, and antioxidants that support women's health.
Power of Low-Calorie, High-Volume Foods
Increased Satiety and Reduced Cravings
While the concept of negative calorie foods may be a myth, there are genuine benefits to incorporating low-calorie, high-volume foods into your diet. These foods can promote feelings of fullness and reduce overall calorie intake, making them valuable allies in weight management efforts. Fibre, in particular, plays a crucial role in promoting satiety. The NHS recommends that adults aim for at least 30g of fibre per day
Foods high in fibre, such as vegetables, fruits, and whole grains, can help women feel fuller for longer periods, potentially reducing overall calorie consumption. Examples of low-calorie, high-fibre foods include:
- Apples (95 calories, 4.4g fibre per medium apple)
- Carrots (52 calories, 3.6g fibre per 100g)
- Lentils (230 calories, 15.6g fibre per cup, cooked)
Essential Nutrients for Overall Health
Low-calorie foods can be incredibly nutrient-dense, providing essential vitamins, minerals, and antioxidants that are crucial for women's health. For example
- Leafy greens are rich in folate, important for women of childbearing age
- Berries are high in antioxidants, which may help reduce the risk of certain cancers
- Lean proteins provide essential amino acids for muscle maintenance and repair
- Whole grains offer B vitamins and minerals important for energy metabolism
By focusing on these nutrient-rich, low-calorie foods, women can support their overall health while managing their weight effectively.
Conclusion
The myth of negative calorie foods, while appealing, is not supported by scientific evidence. Instead of pursuing this concept, we would be better served by focusing on building a balanced, nutritious diet rich in low-calorie, high-volume foods that provide essential nutrients and promote satiety. Remember, sustainable weight management is about creating long-term healthy habits rather than seeking quick fixes. By incorporating a variety of nutrient-dense, low-calorie foods into your diet and following evidence-based guidelines like the NHS Eatwell Guide, you can work towards your weight management goals while supporting your overall health and wellbeing. Always consult with a registered dietitian or healthcare professional for personalised advice tailored to your individual needs and health status. With the right approach and support, you can develop a healthy relationship with food that serves you well for years to come.
References
- Buddemeyer, K. M., Alexander, A. E., & Secor, S. M. (2020). Negative calorie foods: An empirical examination of what is fact or fiction. bioRxiv. https://doi.org/10.1101/586958
- National Health Service. (2023). The Eatwell Guide. https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/the-eatwell-guide/
- National Health Service. (2023). Why is fibre important? https://www.nhs.uk/live-well/eat-well/digestive-health/why-is-fibre-important/
- Public Health England. (2020). Overweight adults. https://fingertips.phe.org.uk/search/overweight#page/3/gid/1/pat/6/par/E12000004/ati/102/are/E06000015/iid/93088/age/168/sex/4/cat/-1/ctp/-1/yrr/1/cid/4/tbm/1
- Ravn, A. M., Gregersen, N. T., Christensen, R., Rasmussen, L. G., Hels, O., Belza, A., Raben, A., Larsen, T. M., Toubro, S., & Astrup, A. (2013). Thermic effect of a meal and appetite in adults: an individual participant data meta-analysis of meal-test trials. Food & Nutrition Research, 57(1), 19676. https://doi.org/10.3402/fnr.v57i0.19676
- University of Sydney. (2021). The thermic effect of food. https://www.sydney.edu.au/science/news-and-events/2021/03/09/the-thermic-effect-of-food.html