By Diarmuid Cavanagh
Introduction
In recent decades, our lifestyle has undergone dramatic changes due to a complex mix of social, environmental, and economic factors. These shifts have led to an increased food supply, higher energy availability, and more calorie-dense diets, all while physical activity levels have declined. Understanding how these changes interact with our natural survival instincts is crucial for effective weight management and health optimization. Humans have an innate drive to seek foods that provide the highest energy yield, meaning we tend to go for foods with the most calories with the least effort to obtain. In today’s world, this tendency can pose significant challenges. In this blog, I will share strategies to help counteract our biology and achieve fat loss goals. We will delve into the science behind these changes and explore practical strategies for achieving and maintaining a healthy body weight.
The Complexity Of Bodyweight
Source: Blundell, John & Baker, Jennifer & Boyland, Emma & Blaak, Ellen & Charzewska, Jadwiga & Henauw, Stefaan & Frühbeck, Gema & Gonzalez-Gross, Marcela & Hebebrand, Johannes & Holm, Lotte & Kriaucioniene, Vilma & Lissner, Lauren & Oppert, Jean-Michel & Schindler, Karin & Silva, Ana & Woodward, Euan. (2017). Variations in the Prevalence of Obesity Among European Countries, and a Consideration of Possible Causes. Obesity facts. 10. 25-37. 10.1159/000455952
Energy Balance: A Key Concept
At the heart of weight management lies the principle of energy balance, which is simply the relationship between calories consumed through food and calories expended by the body for daily functions (such as digestion, breathing, and physical activity). To maintain body weight, energy intake must match energy expenditure. When intake exceeds expenditure, weight gain occurs, while a deficit leads to weight loss. While weight loss is straightforward in theory, maintaining a caloric deficit becomes challenging when balancing our social lives, busy schedules, and the ever-present temptation of hyperpalatable foods.
Your Total Daily Energy Expenditure (TDEE) is the total amount of calories you burn in a day. It’s made up of several components, each contributing to how much energy your body uses for different activities. These include:
- Basal Metabolic Rate (BMR) – The Baseline (~60-70% of TDEE)
BMR is the energy your body needs to maintain basic functions while at rest, like breathing, circulating blood, and regulating body temperature. This is the largest part of your TDEE and is influenced by factors like age, gender, body size, and muscle mass. Even when you’re doing nothing, your body is still burning calories to stay alive.
- Thermic Effect of Food (TEF) – Energy to Digest Food (~10% of TDEE)
TEF is the energy your body uses to digest, absorb, and metabolise the food you eat. Different macronutrients (protein, fat, carbohydrates) require different amounts of energy to process, with protein having the highest thermic effect.
- Non-Exercise Activity Thermogenesis (NEAT) – Daily Movement (~15-30% of TDEE):
This is the energy you burn through non-exercise movements, such as walking, fidgeting, cleaning, or even standing. NEAT can vary significantly depending on your lifestyle. People with more active jobs or daily routines tend to burn more calories through NEAT. - Physical Activity:
This is a combination of both Exercise and NEAT and represents all energy expenditure related to movement.
Main Drivers of Body Weight Regulation
We have two predominant drives of body weight regulation, homeostatic and non-homeostatic.
Homeostatic Regulation: This refers to the biological systems that manage hunger and energy expenditure to maintain stable weight and energy availability. Hormonal signals, such as insulin, leptin, and ghrelin, play a crucial role by communicating with the brain to adjust hunger, energy intake, and expenditure as needed. There are both acute and chronic homeostatic regulatory mechanisms. For instance, leptin regulates long-term energy stores by providing feedback to the brain about body fat levels; as body fat decreases, our drive to consume calories increases. In contrast, ghrelin is an acute homeostatic mechanism it increases hunger when short-term food availability is low.
Non-Homeostatic Regulation: This relates to external and psychological factors that influence eating behaviour, such as emotional eating, stress, availability of food, and social settings. In modern societies, we are often exposed to highly palatable, calorie-dense foods that can override our homeostatic controls, leading to overconsumption and bodyweight accumulation.. These external cues often increase hedonic eating (eating for pleasure), even when the body doesn’t need energy.
Geek Box: The Neuroendocrinology of Satiety
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Biggest levers to pull for Fat- Loss
As mentioned earlier, fat loss is a complex topic influenced by social, cultural, and economic factors. However, when focusing purely on nutrition, two key aspects of food that drive excessive calorie consumption are palatability and calorie density. Understanding these factors can help you make better food choices that support fat loss.
Palatability refers to how pleasurable and rewarding a food is to eat. Foods high in sugar, fat, and salt that have had their water content decreased tend to be hyper-palatable, meaning they trigger the brain’s reward system, making you want to eat more, even if you’re not hungry. Think of processed snacks, fast food, and sugary desserts—they’re designed to be so tasty that they’re hard to stop eating. These foods can lead to overeating because they don’t necessarily make you feel full or satisfied, even when you’ve consumed a lot of calories. Research suggests that hyperpalatable foods can override natural satiety signals, making you overconsume calories.
Calorie Density:
Calorie density refers to the number of calories in a given weight of food. Foods that are high in calorie density pack a lot of calories into a small amount, making it easy to consume more than you need without feeling full. Foods high in dietary fat (any also free sugars) tend to be the most calorie dense, so being mindful of your consumption of oils, baked goods and processed snacks.
On the other hand, low-calorie density foods, such as fruits, vegetables, lean proteins, and whole grains, provide fewer calories for the same weight/volume, allowing you to eat more while consuming fewer calories. There is a considerable amount of data indicating that calorie density is the main drive of how many calories we consume and thus weight loss.
If your goal is fat loss, you shouldn’t focus on eating less; instead, aim to eat more, especially foods with low calorie density. This strategy will make your meals more satiating, decrease the chances of snacking and grazing throughout the day, and importantly, help you consume fewer calories overall.
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