Energy Balance Regulation Mechanism for Dogs and Cats. 

All animals require energy for supporting bodily functions. Growing animals require more energy than their body uses because they need to generate new tissue. Mature animals need excess energy for reproduction. When food absorbs too much excess energy, the animal body stores it as fat. Various factors need to be considered to adjust the energy intake of food for pets. Let's dig deeper into the concept of energy balance.

Energy Expenditure

There are three major components of energy expenditure

• Basal Metabolic Rate
• Voluntary Muscular Activity
• Dietary Thermogenesis

Basal Metabolic Rate and Resting Fed Metabolic Rate 

Basal Metabolic Rate (BMR) is measured after an overnight fast. It represents the minimum energy requirement for the body to maintain its cellular integrity. Resting Fed Metabolic Rate (RFMR) includes thermogenesis after food intake on top of BMR. These two concepts are the main energy expenditures of the body. 

BMR and RFMR are directly proportional to the body's total lean mass and volume of the body. The pet that has more lean muscle will need more energy to maintain tissue function. 

BMR and RFMR may account around 60-70% of total energy requirement. 

Voluntary Muscular Activity

This section, as noted, is voluntary. Therefore, it may account for up to 30 percent of total energy expenditure. The more active the pet is, the greater the energy requirement by muscular activity. 

Dietary Thermogenesis

It is also called the specific dynamic effect of food or meal-induced thermogenesis. This section may account for up to 10 percent of energy expenditure. Animal bodies generate heat while breaking down big food components into smaller building blocks. This procedure also involves converting an existing component into something else. This is the cost of digestion, absorption, metabolism, and storage of nutrients. 

In dogs, the process can occur in two phases; the cephalic phase is the moment food enters into the body, and the postprandial phase is the 6 hours after the food enters into the body. 

The feed intake rate affects dietary thermogenesis. Cats eat more frequent meals, and thus they have higher dietary thermogenesis losses than dogs. 

Other factors, such as emotional stress, can also increase this. 

We also need to account for adjustments to temperature. In colder climates, the body uses more thermogenesis to warm up. This is called nonshivering thermogenesis. 

General Factors to the BMR

The BMR is affected by the age, reproductive status, lean tissue, hormonal status, and calorie restriction. For example, taking lower calories decreases the lean tissue in the body; thus, lower energy is needed, and this situation also impacts the hormone level. We also understand this concept based on our own bodies. 

Reproductive state is also important. Neutered pets require less energy. Therefore, there are special diets for neutered pets. 

Regular exercise is essential for maintaining a healthy basal metabolic rate (BMR). All animals require some physical work to keep lean muscle and energy expenditure in equilibrium. 

Internal Controls for Food Intake

Internal and external signals actually regulate food intake. This method has been tested for lab animals and also provides insight into other species as well. 

Gastric distention, physiological response to sight, sound, and smell of food, changes in plasma concentrations of specific nutrients, hormones and peptides.  are general internal stimuli. 

External stimuli are food availabilty, timing and size of meals, food composition and texture, and diet palatability. 

Food causes stomach distention, which triggers the release of GLP-1 and cholecystokinin (CCK). These two hormones signal short-term satiety. Stomach distention also signals the vagus nerve for satiety. 

The second physiological response is the ileal brake. This represents small intestine fullness up to the ileum. 

Ghrelin is produced by the stomach and stimulates appetite. It peaks prior to meal initiation. 

I cells in the duodenum and jejunum release CCK in response to protein and fat. 

L cells in the ileum and colon release GLP-1 and peptide YY to signal satiety. These two hormones promote slower gastric emptying, which increases feelings of satiety and activates the ileal brake. 

Leptin is produced by adipose tissue and tells the body to stop eating. The higher the adipose tissue is, the higher the leptin levels. However, obese animals have lower leptin sensitivity; therefore, it does not help them to lose weight. 

Insulin is a hormone that pushes glucose from blood to cells. Thus, lowering glucose peaks in the blood may control appetite. 

Reproductive hormones also impact the hormones of satiety. Neutered animals tend to be obese by eating a lot more food. Reproductive hormones impact the effects of leptin. 

External Controls of Food Intake

Palatable diets can cause overconsumption of food. other factors such as texture, timing, environment is important. 

Dogs have a strong preference for wet, semi-moist, beef, and hot meals. They also prefer sugary and salty flavors. The palatability also increases with fat level. 

Social facilitation tends to increase dogs' intake.