2014 AAHA Weight Management Guidelines for Dogs and Cats*^†

Assess the Patient

In addition to a complete physical exam, the patient health assessment may include relevant laboratory and imaging studies as appropriate to assess for comorbidities that may impact either caloric needs or require additional management (e.g., exercise-limiting orthopedic disease, metabolic/endocrine disorders).

Evaluate the pet’s current body weight (BW), BCS, and muscle condition score (MCS) as part of the health assessment and for determining healthy weight.^21,33 Assessing the MCS along with the BCS will establish a baseline from which you may monitor muscle and fat loss, especially if there is either a comorbid condition (where either the weight loss rate may be lower or the patient is at risk for loss of muscle mass due to the catabolic impact of disease) or the patient is losing weight too rapidly (resulting in loss of muscle mass).

Estimating the pet’s ideal weight helps determine the pet’s caloric requirements and establishes a motivating goal. Some ways to estimate a patient's ideal weight include the following:

1. Historical. Check the medical record for the pet’s weight and BCS history to determine whether it shows a previous ideal weight that correlates to a BCS of 5 out of 9 or 3 out of 5.

2. Calculate the ideal weight from the current BCS if historical weight information is not available. Each BCS ≥ 5 (on a 9 point scale) or half of a BCS ≥ 3 (on a 5 point scale) is equivalent to being 10% overweight.^34–37 For example, a 45 kg Labrador retriever that has a BCS of 8 out of 9 is 30% overweight and its ideal weight is approximately 32 kg (Table 1).

3. Use the percent BF that correlates with the BCS scores to estimate ideal weight using the equation: [current BW × (100 − %BF)]/0.8.³⁷ Note that lean mass is 80% of the ideal BW, assuming 20% BF.

TABLE 1 Summary of BCS Scales and Their Relationship with BF and BW^36,68–71

*Current body weight × (100 − % BF)/0.8. Lean mass is 80% of ideal weight (assuming 20% BF).

BCS, body condition score; BF, body fat; BW, body weight.

View Fullscreen

Although there is not an established criterion in veterinary medicine, for the purpose of this document, the authors define obese as a BCS of ≥ 8 out of 9 (or 5 out of 5). Although studies often do not differentiate overweight pets from obese pets, health risks and clinically apparent disease seem greater in severity as weight gain increases. Long-term studies of pets with various BCS categories against controls are needed to verify that clinical impression. All overweight pets suffer from similar, yet less obvious morbidities, and should be treated with as much urgency for weight loss as obese pets.⁷

It is challenging to accurately determine ideal BW in obese patients that exceed the BCS scale (i.e., > 5 out of 5 or > 9 out of 9, correlating to being > 40% overweight). There is no proven method for adjusting the calculation for severely obese patients, and the above approach may cause an overestimate of the ideal weight. Reassessing the patient as their BCS improves during weight loss allows refinement and more accurate estimate of the patient’s ideal weight.

Assess the Client and Feeding Management

Success for weight loss depends on the client’s willingness, interest, and ability to follow recommendations (i.e., adherence). Assess the client’s readiness to change his/her feeding habits and evaluate opportunities for changing the pet’s management and lifestyle.³⁸ Identify challenges the client has faced in the past with feeding management to effectively tailor the plan to the patient and engage the entire household.

Assess the Current Diet

The diet history can provide valuable information about current caloric intake that can serve as a starting point for the weight loss program and help the veterinarian anticipate potential challenges to the weight loss plan (discussed in detail below). Collect information about total daily intake (i.e., varieties and amounts of foods, treats, chews, and supplements; feeding management; and any use of food to administer medication), with sufficient detail to account for all calories ingested. Anticipate nutritional imbalances when treats and human foods exceed 10% of the total caloric intake.²¹

Evaluate how food plays a role in the client relationship with the pet, such as food used for training, nurturing, or bonding in specific situations. Assess “nonnegotiables” lifestyle aspects that the client seems either unlikely or unable to change and try to incorporate some aspect of those aspects into the plan. Such compromises can help increase adherence and trust moving forward with the weight loss program.

Overall Approach

After the initial assessment is complete, formulate an individualized weight loss plan. The plan should include the determination of the following:

1. Ideal BW

2. Caloric restriction

3. Food selection and treat allowance(s)

4. Feeding management and activity plans

5. Scheduled follow-up

Determine Daily Caloric Intake

The approach to determining the daily caloric goal for weight loss depends on the presentation and history of the patient.³⁹ Any method of caloric restriction is merely a starting point and subject to individual metabolism. Regular monitoring is essential to ensure healthy weight loss and allow for necessary adjustments in caloric intake. Two options for determining the daily caloric requirements for weight loss are the following:

1. Feed an amount to provide 80% of the current caloric intake. That approach may be effective in patients that are overweight and are at a stable weight with an accurate diet history. However, if a pet is actively gaining weight, a greater reduction may be required to promote effective weight loss.

2. Calculate the resting energy requirement (RER) using the pet’s estimated ideal weight then feed a percentage of that amount. Although there is no established standard reduction, feeding 80% of ideal-weight RER is effective and well tolerated.^40,41 Calculate the daily RER for ideal BW in kg using one of the following two equations. Note that the first equation can be used for patients of any weight. The second equation is used for patients weighing 2–25 kg, but note that the second equation is not as accurate as the first equation as it will overestimate the caloric needs of patients weighing either < 2 kg or > 25 kg.

Select a Diet

Select a diet based on the caloric restriction desired, the degree of obesity, and the preferences of the patient and client. Inquire about preferences regarding flavor and dry versus canned foods. Evaluate and prepare a list of diet options that vary within those parameters if the first or second choice does not meet with acceptance from the client or pet. Determine availability and affordability concerns that might influence diet selection.

Before starting a plan, make sure that everyone involved in the pet’s care is interested and receptive, ensuring that the plan is practical and feasible for the client’s abilities and lifestyle. Then calculate the daily food dose and translate that dose into quantities of cans and/or cups/day. If possible, weigh dry food on a scale because measuring with a cup may be imprecise, particularly with the small amounts needed for cats and small dogs (calculate the food dose using the kcal/kg obtained from either the pet food label or the manufacturer).⁴² Incorporate a treat allowance of up to 10% of total calories into the daily caloric goal. Explore, address, and realign client expectations if necessary.

Essential nutrients in pet foods are balanced according to caloric content, so when portion size (and thus calories) is reduced, so are the amounts of essential nutrients. A review of the process for a comprehensive analysis of nutritional adequacy of a diet is beyond the scope of these guidelines; however, evaluating a diet for sufficient protein is an important step for weight loss plans.

Consider dietary protein on an energy basis (in g/1,000 kcal) to evaluate the impact of the proposed reduction of caloric intake on National Research Council recommended allowances (Table 2) For a quick rule of thumb to ensure that the diet contains adequate protein, select foods that provide cats with ≥ 5 g/kg BW and dogs with ≥ 2.5 g/kg BW based on ideal BW (See Evaluating Protein Sufficiency sidebar.).^43–45

TABLE 2 Minimum Protein Requirements in Diets⁷²

BW, body weight; NRC, National Research Council; RER, resting energy requirement.

View Fullscreen

A therapeutic food is defined as a pet food that was purpose formulated to help modulate either a disease or condition. Therapeutic foods are only available either through a veterinary office or with a prescription from a veterinarian. Using a therapeutic weight-loss diet is preferred over using reduced amounts of over-the-counter (OTC) diets because therapeutic diets are more likely to provide adequate nutrient intake when fed in calorically restricted amounts.

Therapeutic weight loss diets are formulated to contain more protein, vitamins, and minerals/calorie than OTC foods, ensuring adequate nutrient intake during caloric restriction. High protein may preserve muscle mass during weight loss and may improve satiety.^46,47 As the effects of aging on protein digestibility are not well understood, senior pets may require closer monitoring of protein intake (and MCS) during weight loss.⁴⁸ Therapeutic foods also may be lower in fat, higher in fiber, and/or higher in moisture to decrease caloric density. That allows clients to feed a greater volume of food with fewer calories.

The role of fiber in satiety for dogs and cats is controversial and likely varies among pets.^46,49–51 The crude fiber analysis, which is required on a pet food label, accounts for only the insoluble fiber fraction and none of the soluble fiber content and is an underestimate of the true fiber content of most pet foods. Diets containing insoluble fiber purportedly have a lower caloric content by volume and may promote satiety, leading to better diet plan adherence.⁴⁶ Insoluble fiber may cause an increase in the volume and frequency of bowel movements.⁵² Discuss that potential effect of fiber with clients when selecting a diet.

Restricting the amount of OTC maintenance food that is fed, especially diets with high caloric density, generally fails to provide satiety for most pets, contributing to poor adherence and client frustration. Restricting amounts of an OTC maintenance diet fed could also lead to deficiency of one or more essential nutrients.⁵³

The current median kcal/cup of therapeutic and OTC dry foods marketed for weight management are 301 kcal/cup (dogs) and 342 kcal/cup (cats).⁵⁴ However, there is wide variation and there are no nutritional or caloric criteria mandated for the terms such as “less active,” “indoor,” “weight control,” “optimal weight,” or “healthy weight.” Products labeled “less” or “reduced” calories or fat have no restriction on calorie or fat content other than being some amount lower than the company's chosen comparison product. Foods with labels stating “lite” or “light” must contain less than a certain amount of calories/kg set by the American Association of Feed Control Officials (AAFCO), although there is no restriction on calories/cup or can.²² For specific definitions and amounts that qualify as “light,” see the AAFCO 2013 Official Publication.²² Due to the wide variability of products with such labeling, achievement of weight loss requires careful evaluation of those products on a case-by-case basis.

When advising clients about amounts to feed, it is best to do so based on a caloric target, not just a variation on the label range. Pet foods that show similar caloric content/cup or content/can may show entirely different recommendations about the amount to feed. Compare the caloric density, not the label feeding amounts, to determine caloric intake.

In some instances it may be appropriate to adjust volume alone and not change to a therapeutic diet if the pet can lose weight with modest caloric restriction and without feeding below the label guidelines to provide calories for ideal weight. That process will ensure the pet receives adequate nutrients. For example, that approach may apply to either cats being transitioned to meals from free feeding or to pets just slightly overweight and easily able to increase activity.

There is little to no evidence showing that any nutritional supplement aids in weight loss.⁵⁵ There is one FDA-approved pharmaceutical^a that is currently available for the management of obesity in dogs. That medication was evaluated in a safety and efficacy study up to 1 yr’s duration when used with a maintenance diet.⁵⁶ As with any medication, it may not be appropriate for every patient.

Suggested Follow-up Procedure

Consider some of the following suggestions when following up with the patient and clients:

• Ask open-ended questions to solicit client observations and concerns. Provide positive reinforcement.

• Record BW, MCS, and BCS. It may be useful to show the client measurements of either girth or abdominal circumference to emphasize losses.

• Take a picture of the patient. Create a chart to monitor and show progress.

• Calculate the rate of weight loss using the calculation:

  • The desired rate of weight loss in dogs is 1–2%/wk, and in cats is 0.5–2%/wk.

  • Modify the rate of weight loss in growing pets < 1 yr of age (see previous comments about feeding for growth). Depending on patient age, the focus may be to slow weight gain rather than to cause weight loss.

  • Anticipate a possible slower rate of weight loss in patients with a comorbid condition (such as hyperadrenocorticism or hypothyroidism) either until or unless the primary disease is addressed.

• If MCS decreases, confirm adequate protein intake and evaluate the patient for either too-rapid weight loss or a comorbid condition that intensifies catabolism (e.g., diabetes, renal disease, hyperthyroidism), and adjust intake to reduce the rate of weight loss.

• If the desired weight loss is achieved, congratulate the client and identify the next target weight.

• If weight loss is greater than the above-described desired rates, increase calories by 10% and monitor response.

Reassess if Weight Loss Is Insufficient

If the desired weight loss is less than the above-described desired rates, consider the following:

• Evaluate either adherence or other influences that may have tempered results and suggest alternatives.

• If adherence is verified and there is no evidence of risk, reduce calories by 10–20% and/or change activity recommendations and identify the next benchmark.

  • In the authors’ experience, to achieve weight loss, most patients can tolerate caloric restriction as low as 60% of RER of ideal BW without adverse clinical signs.^64,65 Warn clients that that approach will likely differ from feeding instructions on the label.

  • More aggressive caloric restriction (< 60% RER) increases the risk of nutritional deficiencies and undesirable pet behavior that will test the client’s commitment and adherence. Both commercial and therapeutic diets may lack adequate levels of essential nutrients at that level of caloric restriction. Cats may also have increased risk of hepatic lipidosis.

  • Consult with or refer to a board-certified veterinary nutritionist for clients with pets requiring < 60% RER to achieve weight loss.

• Schedule the next weight check or telephone follow-up.

Maintain Weight Loss Once Goals Are Achieved

Once the pet has reached its ideal BW, careful monitoring is essential to avoid weight regain. Some pets may have a propensity to quickly regain excess BW after a period of weight loss if healthy lifestyle habits are not continued.

Selection of a diet for BW maintenance is based on the pet’s metabolic needs and client preferences, but during maintenance many pets still require relatively low caloric intake.⁴⁰ When faced with caloric restriction, some pets’ metabolism may reset at a lower rate and, thus, they may require greater caloric restriction than expected after the ideal BW has been achieved.⁶⁶ Some pets may plateau at an ideal BW and require no change in intake from that used during the weight loss program for weight maintenance going forward.

If the patient is still losing weight once the ideal BW is achieved, increase caloric intake by 10% to change from weight loss to weight maintenance. Monitor q 2 wk until stable BW is achieved then monitor monthly to make sure ideal BW is being maintained, making adjustments if necessary. It may take several monthly recheck exams to determine appropriate maintenance energy requirements.